UC-NRLF 


T  A 


SB 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 


Class 


Rust 

Prevention 


OF  THE 

f  UNIVERSITY  ! 


By 

M.  Stern 


8ENEKAL 


Copyrighted,  1907 
By  L.  M.  STERN, 
Cleveland,  Ohio. 


OF  THE 
UNIVERSITY 

OF 

F( 


RUST 
PREVENTION 


A  TREATISE 

On  the  preservation  of  Structural  Steel 
used  in  bridges,  buildings,  fire  escapes, 
etc.,  and  Sheet  Steel  used  in  buildings, 
metal  siding,  roofing,  smokestacks, 
boiler  fronts,  and  standpipes,  etc. 

FOR 

Anyone   having  in  charge  their  mainte- 
nance.   Also  property  owners,  architects 
engineers  and  metal  workers,  etc. 

By  L.  M.  STERN 


174580 


INTRODUCTION. 

The  use  of  steel  lias  increased  so  rapidly  within  the 
past  ten  years  that  the  keen  competition  in  cost  of  pro- 
duction between  the  manufacturers  thereof,  has  caused 
an  enormous  amount  of  this  metal  (particularly  in  Sheet 
Steel  and  Terne  Plates  for  exterior  use)  to  be  thrown 
upon  the  market,  of  a  quality  unsatisfactory  to  those  who 
have  to  shoulder  the  responsibility  of  its  proper  main- 
tenance. 

Since  the  advent  of  the  Bessemer  process  of  making 
steel  cheaply,  the  use  of  "  charcoal  iron  "  has  compara- 
tively decreased.  Iron  ore  is  very  rarely  reduced  to  pure 
metallic  iron  for  commercial  purposes,  consequently  the 
foreign  substances  which  have  not  become  eliminated 
from  it  constitutes  part  of  the  material  entering  into  its 
transformation  into  steel. 

The  progress  of  disintegration  of  steel  exposed  to  re- 
actionary agencies  largely  depends  upon  the  quality  of 
the  metal,  nickel  steel,  for  example,  being  but  very 
slightly  susceptible  to  corrosive  action,  while  Bessemer 
process  steel  being  the  reverse. 

The  intention  of  this  treatise  is  to  deal  briefly  with 
the  protection  of  the  surface  of  the  metal,  so  that  cor- 
rosive action  may  be  prevented  from  exterior  sources,  and 
in  pursuing  this  course,  we  must  of  necessity  carry  on 
the  discussion  with  the  understanding  that  the  steel  or 
iron  exposed  to  corrosion  is  of  the  quality  which  ordinar- 
ily comes  from  the  mill,  leaving  the  question  of  placing 
cheap  and  better  steel  upon  the  market  for  structural 
purposes  to  those  who  manufacture  it. 

There  are  a  great  many  paint  manufacturing  con- 
cerns who  make  ridiculous  and  absurd  statements  in 
their  advertising  matter,  in  the  claims  which  they  make 

4 


regarding  wonderful  properties  possessed  by  a  material 
which  they  offer  for  sale  to  prevent  corrosion  and  rust 
on  all  kinds  of  metal  work. 

One  large  concern  advertise  that  they  are  the  sole 
manufacturers  who  own  a  mine  yielding  graphite  of 
such  a  peculiar  flake  form  that  paint  made  with  it  pos- 
sesses the  wonderful  properties  of  the  flakes  arranging 
themselves  like  the  shingles  on  a  roof  or  the  scales  on  a 
fish,  during  the  progress  of  painting  a  surface  with  it, 
claiming  as  a  result  thereof,  that  "  the  flakes  so  arranged 
would  protect  the  oil  in  the  interstices  from  evaporation 
or  excessive  oxidation."  This  manufacturer  fails  to  state 
what  form  these  scales  would  take  if  the  painter  would 
forget  himself  and  use  his  brush  in  the  usual  manner, 
plying  it  back  and  forth  on  the  surface  so  that  the  paint 
would  draw  from  both  sides  of  the  brush. 

The  property  owner  should  post  himself  sufficiently 
to  be  able  to  guard  against  deception  and  fraud.  The 
painter  cannot  be  depended  upon  for  any  definite  knowl- 
edge of  metal  preservation.  He  either  finds  it  unprofit- 
able to  waste  his  time  thinking  about  the  matter,  or  has 
no  inclination  to  have  his  paint  cost  him  more  than  what 
is  absolutely  necessary — hence  his  recommendations  and 
advice  are  more  often  given  .than  asked  for. 

Since  the  author's  first  treatise  on  this  subject,  pub- 
lished in  1901,  extensive  practical  tests  of  various  pig- 
ments and  liquids  for  their  protective  durability  have 
been  under  his  close  surveillance  'in  various  sections  of 
the  country,  covering  a  wide  range  of  climates.  More 
truths  have  been  revealed  regarding  the  most  suitable 
protective  coating  to  resist  the  particular  climate  or 
exposure  at  hand,  and  it  is  to  be  hoped  that  this  treatise 
will  contribute  enough  light  on  this  subject  to  induce 
the  architect,  engineer  or  property  owner  (either  having 
charge  of  construction  work  or  the  maintenance  of  the 
work  after  completion)  to  be  more  cautious  in  the  selec- 
tion of  the  most  suitable  materials. 

5 


The  author  desires  it  to  be  borne  in  mind  that  as  his 
livelihood  depends  upon  the  sale  of  all  kinds  of  materials 
for  the  prevention  of  rust,  any  influence  or  assistance 
that  the  reader  can  extend  toward  their  purchase  from 
him,  will  be  duly  appreciated,  and  that  the  same 
judgment,  resolution  and  practical  experience  which 
prompted  the  issuance  of  this  treatise  will  be  devoted  to 
the  interest  of  those  so  inclined. 

Theories  and  the  chemistry  of  paints  will  herein,  as 
far  as  practical,  be  avoided,  and  a  strict  adherence  to 
practical  knowledge  maintained  as  faithfully  as  possible, 
so  that  the  ordinary  person,  whether  experienced  or 
otherwise,  requiring  some  good  general  pointers  on  the 
subject  may  find  this  treatise  of  some  practical  and 
financial  benefit. 

Very  truly  yours, 

L.  M.   STERN, 

571  EAST  NINETY-NINTH  STREET,  CLEVELAND,  OHIO. 


RUST   PREVENTION. 


Chapter  I. 

I  run  Rust  and  Its  Formation. 

Circumstantial  evidence  convinces  us  that  iron  at  one 
time,  say  thousands  of  years  ago,  might  easily  have  been 
or  in  fact  was  distributed  over  portions  of  the  earth  in 
a  metallic  state  and  that  the  subsequent  action  of 
oxygen,  sulphur,  silica  and  other  elements  have  con- 
verted it  into  the  state  in  which  it  is  now  found  and 
which  is  commonly  called  iron  ore. 

Iron  ore  resembles  rust  in  appearance  and  not  only 
contains  the  two  important  elements  of  rust,  of  which  it 
principally  consists,  namely  (Fe2O3),  but  it  contains 
other  elements  as  well,  such  as  sulphur,  and  silica,  &c. ; 
hence  it  remains  for  man  to  undo  what  nature's  labora- 
tory has  done  for  centuries  and  separate  the  elements 
closely  united  in  the  composition  of  the  ore  and  thus  ob- 
tain the  metallic  iron  for  use  in  the  arts. 

Rust  is  a  reddish  brown  deposit,  generally  noticed  on 
the  surface  of  steel  and  iron  after  having  undergone  de- 
terioration by  chemical  change,  due  to  exposure  to  agen- 
cies, causing  its  formation.  It  ordinarily  consists  mostly 
of  oxide  of  iron,  together  with  other  minor  substances 
and  water. 

The  compound  known  as  oxide  of  iron  consists  of  the 
chemical  combination  of  two  parts  of  iron  with  three 
parts  of  oxygen,  commonly  expressed  in  chemistry  by  the 
symbol  (Fe2O3)  the  first  two  letters  representing  the 
Latin  term  Ferris,  meaning  iron  and  the  letter  "O  repre- 
senting the  word  oxygen. 

For  the  reason  that  iron  oxide  is  an  hydroscopic  salt, 
it  has  the  property  of  absorbing  water,  intimately  holding 
a  portion  of  it  in  close  affinity  with  its  molecules :  this, 
however,  does  not  change  its  chemical  composition  to  any 
appreciable  extent,  for  the  reason  that  the  water  does 
not  form  a  chemical  solution  with  the  oxide.  Thus,  rust 
is  termed  a  hydrated  oxide  of  iron,  which  is  symbolized 
in  chemistry  as  Fe2O3  +  (H2O),  which  is  oxide  of  iron 


plus  water.  This  water  is  free  to  act  on  metallic  iron 
into  which  it  may  come  in  contact,  forming  additional 
rust,  thus  creating  more  room  for  water  absorption  and 
continuing  the  process  of  rust  formation  indefinitely. 

The  chemical  decomposition  of  the  steel  or  iron  by 
the  combination  of  particles  of  the  metal  with  oxygen  is 
accelerated  by  frequent  contact  of  the  metal  with  oxygen 
in  a  condensed  form,  such  as  is  found  in  liquids,  and  its 
subsequent  evaporation  in  the  presence  of  gaseous  oxygen 
such  as  atmospheric  oxygen,  &c. 

Thus  a  solution  of  oxygen  in  the  form  of  rain,  dew 
or  other  forms  of  moisture,  when  deposited  on  an  iron 
surface  and  quickly  evaporated,  will  rust  the  surface 
much  more  readily  than  if  the  water  or  moisture  were 
maintained  on  the  surface.  In  high  and  dry  climates, 
where  the  proportion  of  pure  oxygen  is  greater  in  the 
atmosphere,  iron  and  steel  will  not  rust  as  quickly  as  in 
low  damp  valleys,  where  fogs  and  heavy  dews  are  preva- 
lent, so  that  the  conjoint  action, of  atmospheric  oxygen 
and  water  or  other  forms  of  moisture  may  act  upon  the 
surface. 

A  piece  of  steel  can  be  seen  to  rust  in  a  few  moments 
time  after  the  evaporation  of  water  from  the  surface. 
All  forms  of  iron,  whether  sheet  iron,  steel,  pig  iron,  cast 
iron,  malleable  iron,  or  any  condition  of  bare  and  un- 
protected iron  or  steel  surface  exposed  to  frequent  re- 
newals of  moisture  and  atmospheric  oxygen,  become 
rusted,  and  the  aggressiveness  taken  by  this  form  of  re- 
agent depends  not  only  on  the  frequency  of  evaporation 
and  renewal  of  moisture,  but  on  the  cleanliness  of  the 
surface  thus  exposed  and  temperature  of  and  active  quali- 
ties of  the  water,  coacting  with  the  atmospheric  oxygen 
as  well,  together  with  the  chemical  composition  of  the 
steel,  some  grades  of  steel  being  attacked  far  more  read- 
ily than  others. 

The  writer  has  seen  steel  girders  on  bridges  so  badly 
rusted  that  portions  of  them,  when  coming  in  contact 
with  the  pressure  of  the  hand,  would  slough  away  like 
a  rotten  log.  Some  rusted  sections  would  be  directly  be- 
low the  coating  of  paint,  which  would  be  in  an  almost 
perfect  condition  on  the  surface.  This  rusted  metal  would 
be  piled  up  in  layers,  one  upon  the  other,  completely  af- 
fected through  the  entire  thickness  of  the  original  beam, 
which  upon  examination  would  reveal  the  fact  that  the 
steel  had  been  imperfectly  rolled  or  refined  during  the 

8 


process  of  manufacture,  resulting  in  seams  resembling  an 
imperfect  weld,  which  would  accumulate  rust  and  by  the 
admission  of  moisture  in  the  interstices  and  the  contrac- 
tion and  expansion  of  the  metal  would  loosen  up  the 
crevices  between  the  layers  so  that  they  could  be  rent 
asunder  with  a  pocket  knife,  like  sheets  of  mica. 

Steel  kept  under  water,  in  the  ground  or  set  in  cement, 
which  will  admit  oxygen  and  moisture  and  allow  the 
same  to  be  evaporated,  is  eventually  doomed  to  prema- 
ture rust  and  decay. 

All  of  the  hydroscopic  salts,  especially  common  salt, 
magnesium  chloride,  potassium  chloride,  ammonium 
chloride  aid  and  assist  in  forming  rust. 

Carbonic  dioxide  gas  (CO2)  which  is  constantly  being 
poured  into  the  air  from  our  chimneys  and  our  lungs, 
sulphuretted  hydroge.ii  from  coke  ovens  and  furnaces, 
likewise  attack  the  metal  surface  and  assist  in  the  for- 
mation of  the  compound  which  we  call  rust. 

.Water  impregnated  with  caustic  alkali  will  not  rust 
steel  readily,  provided  the  steel  be  immersed  in  a  bath  of 
the  same  and  be  continually  kept  beneath  the  surface. 

Almost  all  of  the  acids,  when  diluted  with  consider- 
able water,  rust  iron  and  steel  considerably,  and  strange 
as  it  may  seem  the  fact  nevertheless  remains,  that  a 
great  many  acids  attack  steel  more  vigorously  when  di- 
luted with  water  than  otherwise.  This  fact  may  be  due 
to  the  oxygen  in  the  water  co-operating  with  the  acid  in 
chemically  decomposing  the  surface  of  the  steel  and  con- 
verting the  same  into  rust. 

Steel  once  rusted  is  more  readily  attacked,  and  its 
decomposition  takes  place  more  readily  than  when  in  its 
original  condition,  unless  the  surface  has  been  divested 
of  all  metallic  oxidation  prior  to  the  renewal  of  the  for- 
mation of  this  compound. 

The  tensile  strength  of  rust  cannot  be  relied  upon  for 
any  practical  purposes,  and  it  is  almost  safe  to  say  that 
the  amount  of  steel  surface  attacked  by  corrosion  has 
not  only  lost  its  equivalent  amount  of  strength  and  is 
burdened  by  the  weight  of  the  rust,  but  the  factor  of 
safety  is  lowered  to  the  basis  of  the  weakest  point 
formed  by  corrosion. 

The  formation  of  rust  may  be  classed  as  arising  from 
two  different  conditions,  which  we  will  assume  for  the 
purpose  of  argument  are: 

Primary  Condition. — Those  conditions  where  the  sur- 


face  has  been  exposed  to  ordinary  rust  generating  in- 
fluences,  such   as  ordinary  'atmospheric  conditions. 

Secondary  Condition. — Those  conditions  where  tae 
surface  has  been  attacked  either  by  substances  attached 
to  the  surface  or  by  the  action  of  extraordinary  atmos- 
pheric conditions.  (Atmospheres  impregnated  with  acid 
fumes,  &c.) 

Rust  can  be  economically  removed  very  readily  by 
mechanical  means,  and  this  is  the  only  means  by  which 
it  can  be  done  on  a  large  scale  successfully.  Abrasion  and 
hammering  with  a  tool  conveniently  handled  and  ap- 
plied to  the  surface  is  the  method  recommended  by  the 
author.  Flat  surfaces  that  will  admit  of  the  use  of  a 
steel  wire  brush  should  be  gone  over  vigorously,  both 
lengthwise  and  crosswise,  so  that  all  loose  scales  and  ir- 
regular masses  may  become  detached;  then  a  hammer, 
file  and  cold  chisel  should  be  brought  into  use,  as  well 
as  a  painter's  wall  scraper  or  putty  knife  wherever  there 
is  an  accumulation  of  any  thick  incrustation.  After  this 
treatment  has  been  completely  accomplished,  the  steel 
brush  should  again  come  into  play,  as  before,  after 
which  a  vigorous  application  of  coarse  emery  cloth  or 
sandpaper  should  be  employed,  in  lieu  of  which  steel 
wool  or  steel  shavings  may  be  substituted  for  the  final 
removal  of  all  loose  and  scaly  formations  of  rust. 

After  the  above  treatment  is  completed  in  as  thorough 
a  manner  as  possible,  a  good  heavy  bristle  brush  should 
be  used  to  dust  out  the  finely  powdered  rust,  and  then  the 
surface  should  be  finally  wiped  off  clean  with  a  dry  cloth. 
The  hot  blast  from  a  painter's  torch  may  sometimes  be 
found  to  work  to  good  advantage  in  evaporating  as 
much  moisture  as  possible  out  of  the*  rust,  which  opera- 
tion may  result  in  reducing  considerable  of  it  into  a 
powdered  state. 

The  use  of  the  sand  blast  produces  the  best  results, 
but  this  is  often  too  expensive  a  process. 

Any  vigorous  treatment  for  the  removal  of  rust  may 
be  recommended  in  so  far  that  the  treatment  thus  af- 
fected does  not  crack,  break  or  otherwise  injure  the 
metal  nor  leave  any  condition  liable  to  impair  the  means 
of  protection  afterwards  to  be  employed. 

.  A  wet  process,  or  the  various  applications  of  oils,  such 
as  benzine,  gasoline,  creosote  oil  has  been  recommend- 
ed by  many  users  of  the  same,  and  these  may  be  used  to 
advantage  to  penetrate  deeply  into  rust  incrustations 

IO 


and  thereby  aid  the  hot  blast  from  the  painter's  torch 
in  evaporating  moisture,  as  heretofore  mentioned.  The 
writer  has  not,  however,  found  them  to  possess  any 
special  beneficial  chemical  properties  in  rendering  rust 
inactive  after  the  oil  had  evaporated  therefrom.  Oil 
once  eliminated  from  rust  leaves  it  in  practically  the 
same  active  condition  as  it  would  had  it  not  been  im- 
pregnated or  covered  with  it. 

The  author  has  found  one  advantage,  however-,  in 
soaking  powdered  rust  with  oils  immediately  prior  to 
its  removal,  and  this  is  that  the  rust  is  capable  of  ad- 
hering to  a  cloth  when  rubbed  on  the  surface  thus  oiled, 
forming  a  sort  of  coagulated  mass  of  rust  paste,  which 
may  be  used  to  great  advantage  in  contributing  friction 
or  grinding  properties,  much  after  the  fashion  of  the 
old  style  "bath  bricks,"  which  were  used  to  clean  and 
brighten  rough  table  ware. 

We  have  observed  the  reasons  why  rust  forms,  and 
we  will  henceforth  turn  our  attention  to  the  measures 
whereby  the  accumulation  of  rust  may  be  prevented :  in 
other  words,  the  ways  and  means  whereby  steel  and  iron 
may  be  maintained  or  kept  free  from  contact  with 
oxygen  and  atmospheric  moisture.  The  ways  and  means 
by  which  the  same  may  be  done  is,  of  course,  to  cover 
the  surface  with  a  noncorrosive  substance;  something 
which  will  not  contain  nor  transmit  any  oxydizing  me- 
dium to  the  surface  of  the  metal.  It  must,  therefore,  a* 
far  as  possible  (for  all  practical  and  economical  reasons), 
possess  the  qualities  of  easy  application,  maximum 
amount  of  protecting  durability  and  a  minimum  amount 
of  cost. 


I  i 


Chapter  II. 

Some  Chemical  Elements  and  Their  Symbols. 

By  chemical  element  we  mean  those  substances  which 
are  not  made  up  of  two  or  more  substances.  They  are 
not  necessarily  distinguished  by  any  external  appear- 
ances, but  are  known  to  science  as  substances  which  can- 
not be  decomposed.  We  can  convert  them  into  thousands 
of  other  substances,  but  in  all  cases  extra  weight  and 
material  has  been  added,  but  none  taken  from  an  element 
composing  a  compound. 

For  illustration,  we  may  decompose  water  by  an 
electric  current,  first  weighing  the  water.  The  hydrogen 
and  oxygen  that  become  separated  we  know  were  in  com- 
bination, and  the  weight  of  both  together  equal  the 
weight  of  the  water,  for  on  combining  them  again  we 
may  thus  prove  that  water  consists  wholly  of  hydrogen 
and  oxygen. 

A  nice  illustration  of  the  combining  of  two  elements 
may  be  shown  by  the  burning  of  finely  pulverized  metal- 
lic iron  in  the  presence  of  oxygen.  The  result  of  a  change- 
is  a  substance  which  we  call  oxide  of  iron.  This  sub- 
stance obtained  has  increased  in  weight,  proving  that  ma- 
terial has  been  added  to  it,  and  not  taken  from  it,  the 
extra  weight  being  due  to  its  combination  with  oxygen. 

This  experiment  illustrates  a  most  remarkable  truth 
in  regard  to  the  substance  we  call  iron.  By  various 
chemical  processes  we  can  produce  from  the  metal  hun- 
dreds of  different  substances,  but,  in  all  cases,  the  con- 
dition of  the  experiment  and  the  relative  weight  of  the 
products  prove  that  material  has  been  added  to  the  iron 
and  not  taken  from  it. 

By  no  chemical  process  whatever  can  be  obtain  from 
iron  a  substance  weighing  less  than  the  metal  used  in  its 
production.  In  a  word,  we  can  extract  nothing  from 
iron  but  iron  ;  in  like  manner  we  cannot  extract  anything 
from  carbon  but  carbon,  nor,  in  fact,  any  material  from 
any  element  but  part  of  the  element  itself. 

In  chemistry  the  initial  letters  of  the  Latin  names 
of  elementary  substances  are  represented  to  denote  one 
atom  of  each  element.  These  are  callerl  chemical  syin- 

12 


bols.  The  symbols  of  these  elements,  which  sometimes 
enter  into  the  composition  of  paints,  oils  or  varnishes,  or 
compounds  entering  into  the  destruction  of  the  same 
while  under  exposure,  are  as  follows: 

Aluminum    Al.       Manganese Mn. 

Barium Ba.       Mercury Hg. 

Calcium    Ca.       Nitrogen    N. 

Carbon    C.       Oxygen    O. 

Chlorine    Cl.       Potassium    K. 

Copper    Cu.       Silicon    Si. 

Hydrogen H.       Sodium    Na. 

Iron   Pe.       Sulphur S. 

Lead   Pb.       Zinc   Zn. 

Magnesium    Mg. 

The  full  list  of  elements  are  set  forth  in  almost  any 
work  on  chemistry.  Those  not  here  mentioned  are  omit- 
ted for  the  reason  that  they  are  rarely,  if  ever,  met  with 
within  the  scope  of  the  subject  here  at  hand  and  would 
only  have  a  tendency  to  burden  the  reader  with  unneces- 
sary and  uninteresting  complications. 


Chapter  III. 

Rust  Prevention. 

Since  we  have  noticed  that  the  exidation,  rusting  or 
corrosion  of  iron  is  due  to  its  chemical  combination  with 
substances  with  which  it  has  uniting  properties,  and  that 
the  resultant  product  is  what  we  call  rust,  primarily  con- 
sisting of  Fe2O3  +  (H2O),  we  necessarily  conclude  that 
we  can  only  prevent  the  formation  of  this  compound  on 
the  surface  of  the  metal  by  maintaining  its  isolation 
from  substances  necessary  for  its  propagation,  thus  reach- 
ing the  foundation  of  its  protection. 

There  are  many  ways  and  means  of  accomplishing 
this,  and  innumerable  substances  may  be  used  for  apply- 
ing on  the  surface  of  the  metal,  all  of  which  have  widely 
different  characteristics,  and  also  great  variation  of 
permanency  or  efficiency ;  but  we  are  interested  chiefly 
in  the  most  economical  and  reliable  method  of  doing  so. 

We  know  that  water  (H2O)  and  atmospheric  oxygen 
alternately  acting  on  the  metal  surface  are  the  most 
prevalent  rust  generating  mediums,  causing  rust,  and 
therefore  should  expect  to  obtain  materials  for  applica- 
tion on  the  surface  of  the  metal  that  are  not  easily  af- 
fected by  these  agents,  or  the  mediums  which  cause  the 
secondary  condition  to  produce  rust. 

The  efficiency  of  protective  coatings  for  metal  sur- 
faces are  entirely  dependent  upon  the  character  of  ex- 
posures, adhesiveness  of  the  coatings,  resistance  to  abra- 
sion, and  other  qualifications,  in  consequence  of  which  we 
are  led  to  investigate  the  various  conditions  in  order 
to  meet  them  in  the  most  economical  and  convenient 
manner  possible. 

Oils  and  greases  of  various  kinds  have  been  used  for 
protecting  metallic  surfaces  from  the  absorption  of  oxy- 
gen. Great  varieties  of  them  are  used  where  the  ex- 
posure is  not  permanent  or  severe,  and  the  oils  or  greases 
are  to  be  removed  easily  after  they  have  served  their 
purpose;  for  example,  machinery,  firearms,  carpenters' 
and  mechanics'  tools,  &c.,  and  even  these,  if  left  out  in 
the  rain,  will  become  rusted  soon  after  atmospheric 
conditions  or  water  obtains  the  mastery  over  the  coat- 

14 


evaporation  or  decomposition.  The  question,  however,  of 
ing,  causing  its  washing  off  by  friction  or  elimination  by 
temporary  prevention  of  rust  by  the  use  of  oils  and 
greases  is  of  small  importance  compared  to  the  protec- 
tion of  costly  steel  and  iron  structures  and  other  large 
metal  surfaces,  and  consequently  these  will  engage  our 
attention  so  that  the  selection  of  the  proper  materials  for 
thie  production  of  protective  coatings  may  be  accom- 
plished in  the  manner  most  desired. 

Various  paints,  oils  and  varnishes  may  be  used,  and 
their  protective  qualities  will  last  as  long  as  they  will 
be  devoid  of  water  absorbing  properties,  and  m&intain  a 
coherent  adhesive  coating  on  the  surface. 

The  author  has  ascertained  by  actual  tests  that  there 
exists  a  wonderful  variation  in  the  aggressiveness  of 
various  pigu-ents  coacting  with  atmospheric  moisture  in 
attacking  a  metal  surface,  when  the  oil  has  dried  out, 
leaving  the  paint  porous  enough  to  absorb  moisture.  It 
svill  then  be  seen  that  a  destructive  agent  finally  en- 
sues from  the  material  which  was  originally  intended  for 
a  protective  addition  to  the  oil. 

Very  often  an  oxide  paint  pigment  is  mixed  writh  oil 
and  used  as  a  protective  coating  for  metal.  The  oil 
neutralizes  temporarily  the  oxidizing  properties  of  the 
pigment  in  question,  but  when  the  dried  paint  becomes 
porous  by  the  disintregation,  excess  oxidation,  or  evapora- 
tion of  the  oil,  the  oxide  pigment  takes  up  moisture,  car- 
ries it  to  the  metal  surface  and  there  conducts  a  process 
of  conjoint  attack  in  generating  rust  that  would  not  be 
possible  with  a  carbon  pigment  used  under  similar  con- 
ditions. 

Porosity  of  a  paint  can  often  be  detected  by  the  ap- 
pearance of  stains  from  moisture  with  which  the  paint 
becomes  saturated,  and  by  cutting  into  the  moistened 
paint  with  a  pocket  knife  a  fair  idea  may  be  had  as  to 
whether  a  fresh  application  of  paint  is  necessary  to  pre- 
vent moisture  from  gaining  admission  through  the  coat 
ing  and  coming  into  direct  contact  with  the  metallic  sur- 
face. 

The  porosity  of  a  paint,  however,  is  very  rarely  taken 
notice  of  in  time  to  prevent  rust,  as  it  often,  while  in 
this  condition,  appears  to  remain  a  coherent,  adhesive 
mass  of  fair  density  and  resistance  to  mechanical  abra- 
sion. The  most  noticeable  feature  which  may  be  easily 
discerned  in  this  respect,  however,  is  that  the  coating 


has  lost  its  glossy  appearance,  and  appears  dead  or  dried 
out,  and  even  in  this  condition  it  is  not  always  porous 
enough  to  admit  moisture  entirely  through  the  coating. 

The  illustration  shows  what  can  be  done  in  the 
laboratory  to  definitely  ascertain  the  amount  of  porosity 
of  any  kind  of  paint  or  varnish.  Owing  to  a  chemical 
phenomenon,  any  dried  coating  of  paint  having  been  ex- 
posed to  the  weather  any  number  of  years  may  be  by 
the  author  easily  removed  from  the  metal  surface  intact 
and  without  injury.  The  paint  thus  removed  can  be  ac- 
curately tested  for  porosity,  elasticity  and  adhesiveness. 


Plate  I. 

and  the  thickness  of  it  may  be  tested  at  different  points 
with  a  micrometer  or  depth  gauge. 

A  simpler  and  more  satisfactory  way  of  testing  or 
ascertaining  porosity  of  a  paint  film  for  the  ordinary 
person,  however,  would  be  to  apply  the  paint  on  sheets 
of  glass,  expose  the  same  to  the  weather  for  from  one  to 
five  years  at  a  convenient  place,  so  that  the  sample  may 
be  taken  down  and  held  up  to  the  light  at  different  stages 
of  exposure,  and  thus  any  ordinary  amount  of  porosity 
can  be  very  readily  seen. 

Paints   or  varnishes   intended  chiefly   for   decorative 

16 


purposes,  that  will  l#st  for  15  years  on  the  inside  wood- 
work of  a  residence,  will  do  well  if  they  last  more  than 
five  years  on  the  outside  woodwork  of  the  same  resi- 
dence, and  would  be  an  exception,  indeed,  if  they  would 
last  over  two  years  on  the  tin  roof  or  gutters,  thus  demon- 
strating the  great  difference  in  exposure  and  consequent 
variation  in  the  decomposition  of  the  paint  on  different 
portions  of  a  house. 

It  remains  for  us,  therefore,  to  compound  paints  for 
specific  purposes,  made  of  such  material  that  will  give 
them  the  greatest  efficiency.  Knowing  why,  \vhere  and 
when  the  different  materials  necessary  for  their  composi- 
tion may  be  used  to  the  best  advantage,  not,  however, 
taking  for  example  the  various  materials  used  to  pre- 
serve or  beautify  wood,  for  while  one  class  of  paint  may 
be  suitable  to  both  wood  and  metal,  this  condition  would 
merely  be  an  incident  when  atmospheric  or  other  severe 
exposures  would  prevail. 

In  a  majority  of  instances  paint  dealers  throughout 
the  country  sell  most  of  the  paint  intended  for  wood 
surfaces  from  $1.25  to  $1.50  per  gallon.  Yet,  when  it 
comes  to  paint  for  metal  roofs,  the  prevailing  condition 
seems  to  be  that  the  dealer  canot  sell  a  paint  for  this 
class  of  work  for  more  than  50  or  75  cents  per  gallon. 
Why?  Because  the  uninformed  possessors  of  false  eco- 
nomical paint  principles  believe  "  If  the  paint  on  the 
visible  exterior  of  the  house,  which  is  expected  to  look 
pleasing  to  the  eye,  cost  a  certain  price,  paint  that  is  put 
up  on  the  roof  and  which  is  not  necessary  to  look  pleas- 
ing to  the  eye,  should  not  cost  half  that  price."  There- 
fore, the  price  that  controls  the  quality  of  paint  on  the 
market  for  metal  roofs  which  are  sold  by  the  dealer  are, 
unfortunately,  kept  down  by  popular  demand. 

Another  reason  for  a  vast  amount  of  cheap  trash  on 
the  market  for  metal  protection  and  called  paint  is  the 
fact  that  the  painter  or  tinner  applies  a  cheap  quality 
so  that  his  own  temporary  profits  may  be  thus  gained. 
Painters  and  tinners  invariably  are  asked  by  their  cus- 
tomers for  prices  "per  square"  for  doing  the  job  (de- 
tails of  quality  and  materials  omitted),  and  in  order  to 
secure  the  work  he  is  tempted  to  make  a  price  consistent 
with  his  chances  of  a  successful  issue.  As  a  rule  the 
tinner  does  not  care  much  whether  the  paint  he  puts  on 
wears  one  or  five  years.  It  makes  no  material  difference 
to  .  him.  It  may  present  a  good  appearance  for  a  few 

17 


months  after  it  is  applied,  and  be  almost  entirely  washed 
off  in  a  year  or  so  afterward. 

There  are  many  paints  that  will  wear  well  for  a 
period  of  from  5  to  10  years  on  sheet  metal  exposed  to 
the  weather,  and  also  on  bridges,  but  the  manufacturers 
of  these  are  compelled  very  often  to  give  a  very  close  bid 
in  order  to  get  a  contract  and  are  compelled  to  use  cheap 
material ;  in  fact,  they  have  often  made  the  statement  to 
those  who  attempt  to  sell  them  high  grade  paint  that 
"  our  customers  will  not  pay  us  any  more  for  our  ma- 
terial with  high  grade  paint  than  if  it  were  coated  with 
the  cheapest  that  could  be  obtained." 


l« 


Chapter  IV. 

Paint  Ingredients,  their  Classifications  and  Functions. 

Paint  ingredients  we  shall  divide  into  two  general 
classes,  namely:  Liquids  and  Solids.  They  consist  of 
the  following: 

1.  Pigments — (dry  powdered,  insoluble  substances). 

2.  Vehicles — (Liquid  materials  for  carrying  the  pig- 
ments). 

3.  Volatile  oils  and  dryers — (Evaporating  oils,  &c.)- 

4.  Soluble    Solids — (Solid    substances    for    dissolving 
into  the  liquids  . 

Pigments  (for  paints)  are  those  dry  powdered  sub- 
stances intended  for  mixing  with  liquids  for  the  purpose 
of  making  liquid  or  paste  paints. 

All  pigments  when  dry  hold  water  freely. 

The  pigments  used  in  metal  preserving  paints  are  all 
derivatives  of  minerals,  on  account  of  their  cheapness 
in  price,  stability  and  durability,  while  those  pigments 
which  are  made  of  vegetable  and  animal  products  are 
used  for  artistic  and  beautifying  purposes. 

Pigments  are  generally  termed  "  dry  colors,"  but  this 
term  is  erroneous,  for  the  reason  that  many  pigments  do 
not  possess  -any  color,  being  merely  white  or  black.  They 
are  likewise  termed  "  dry  paints "  which  term  is  am- 
biguous, for  the  reason  that  dry  paint  is  often  the  sub- 
stance which  results  in  a  liquid  paint  becoming  dry  on 
a  surface. 

The  definition  of  the  word  pigment,  as  above  stated, 
in  order  to  avoid  confusion,  should  be  well  kept  in  mind. 
Pigments  we  separate  into  two  classes : — Natural  pig- 
ments and  chemically  produced  pigments. 

Those  which  are  used  in  the  manufacture  of  pro- 
tective coatings  are,  as  follows: 


Black  pigments. 

White  pigments. 

Yellow,  red  and  brown 

Graphite,  C  
Lamp  black,  C. 

White  lead,  2PbCOs, 
PbH2Oc. 
Oxide  of  zinc,  ZnO  
Zinc  white,  ZnO  
Lead   sulphate,    PbSO4. 

Whiting,  CaCO3  
Barytes  BaSO4 

Yellow  ochre,   Fe2HO6 

Umber,  Fe2HO6+MnHO4 
Iron  oxide,  FeoO-,. 
Venetian     red,     FeoO3+ 
impurities. 
Red  oxide,  Fe2O3  +  im- 
purities. 
Red  lead    Pb3O4 

Barium  sulphate,  BaSO 

Metallic  '  red,    Fe2O2    + 
impurities. 

While  there  are  many  more  pigments  used  than 
these  mentioned  for  metal  preserving  paints,  the  balance 
of  them  are  generally  used  for  their  coloring  properties, 
or  as  a  means  of  deceiving  purchasers  by  false  state- 
ments, as  to  extraordinary  merits,  which  they  are  pre- 
sumed to  possess. 

The  function  of  a  pigment  is  to  thicken  the  vehicle, 
to  make  it  opaque  with  a  suitable  material  or  color,  to 
give  the  paint  a  viscid  body  (viscosity)  and  add  tough- 
ness and  durability  to  the  paints  when  dry.  Some  pig- 
ments accomplish  this  with  a  great  variety  of  results, 
especially  when  more  or  less  of  it  is  used  than  the 
amount  necessary  to  perform  its  maximum  amount  of 
usefulness.  The  exact  amount  of  pigment  or  pigments 
to  be  used  in  making  a  paint  to  possess  the  proper  thick- 
ness when  spread  on  a  surface  to  obtain  the  greatest  ef- 
ficiency in  its  protection  can  only  be  ascertained  by  ac- 
tual tests  for  their  proper  working  qualities  under  the 
brush,  and  also  withstanding  the  kind  of  exposure  met 
with. 

Actual  tests  for  the  durability  of  the  pigment  are 
necessary  in  determining  the  quantity  of  the  pigment  to 
be  used  for  the  reason  that  there  is  such  a  variety  of 
grades  of  pigments  on  the  market,  and  they  possess  an 
individuality  of  certain  capacity  for  absorbing  or  "  tak- 
ing to"  the  oils  used;  that  no  set  rule  can  be  laid  down 
for  the  actual  amount  to  be  used  necessary  to  accom- 
plish the  best  results. 

This  is  especially  true  for  the  reason  that  one  manu- 
facturer's pigment  is  at  variance  in  texture,  freedom 
from  impurities  and  other  qualifications,  from  another's 
which  bear  the  same  name. 

Each  class  of  pigments  has  a  different  effect  upon 
the  drying  or  oxidizing  properties  of  linseed  oil :  Some  of 
these  pigments  retard  the  drying  properties  while  others 
hasten  the  oxidation  to  a  remarkable  degree. 

Among  those  of  the  latter  may  be  mentioned  all  of 
the  pigments  containing  oxygen  in  their  composition. 
Red  Lead  (Pb3O4)  especially.  The  pigments  which  con- 
tain oxygen  prevent  the  formation  of  rust,  while  they 
are  in  combination  w^ith  oils,  but  when  the  oils  either 
evaporate  or  become  excessively  oxidized  so  that  the 
pigments  protrude  through  the  film  of  oil  on  the  dried 
painted  surface,  or  in  fact  loses  so  much  of  the  oil 
through  exposure  that  the  paint  has  become  porous,  it 

20 


then  co-acts  with  moisture  and  atmospheric  oxygen  and 
the  metal  surface  beneath  the  paint  becomes  rapidly  and 
vigorously  attacked,  whereupon  the  very  pigment  which 
was  originally  a  protective  medium  becomes  a  rust  pro- 
ducer. 

The  carbon  pigments  are  elements  and  consequently 
can  only  consist  of  carbon  excepting  where  there  is  an 
impurity  or  an  adulteration  present  and  this  is  not  as 
a  rule  premeditated,  but  rather  accidental,  at  all  events 
they  are  not  generally  found  to  any  such  a  degree  as 
they  are  in  the  lead  or  chemically  produced  pigments 
and  even  when  not  so  the  impurities  in  the  former  are 
invariably  inert  substances  and  do  not  promote  chemical 
activity  in  producing  rust. 

The  carbon  pigments  show  a  far  superior  resistance 
to  the  accumulation  of  rust,  when  the  oils  begin  to  wear 
out  or  become  eliminated  from  a  painted  surface  after 
prolonged  exposure  than  do  the  oxygen  pigments,  more- 
over they  are  not  affected  to  any  extent  by  acids  whether 
in  the  liquid  or  gaseous  form.  Hence,  it  will  be  seen 
that  the  carbon  pigments  are  to  be  preferred,  graphite 
especially,  for  graphite  which  is  also  ^sed  as  a  lubricant 
possesses  such  a  degree  of  fineness  of  texture  that  it 
gives  the  paint  where  it  is  used  as  a  pigment,  such  a 
slippery  surface  when  several  years  dry,  that  it  reduces 
to  the  minimum  the  abrasive  effect  of  water,  snow,  ice  or 
mechanical  abrasion,  etc. 

We  may  easily  destroy  the  efficiency  of  the  best 
pigment  by  the  use  of  admixtures  whereby  the'  pigment 
or  the  oil  become  impaired.  A  course  granular  sub- 
stance added  to  graphite  tends  to  give  to  the  painted 
surface  a  rougher  coating  of  paint  which  serves  as  a 
lodging  place  for  water,  which  adheres  by  capillary  at- 
traction to  the  roughened  surface. 

Pigments  as  powdered  dry  substances  are  fixed  or 
stable  bases,  but  as  coloring  materials  (excepting  the 
carbons)  they  invariably  fade  after  prolonged  exposure, 
and  while  their  stability  as  a  base  may  be  relied  upon, 
the  various  effects  which  the  different  pigments  possess 
in  their  co-active  properties  with  drying  oils  is  more  or 
less  important.  It  is  not  so  important  however,  as  the 
proper  treatment  of  the  oils  to  be  used. 

The  most  undesirable  pigment  mixed  with  the  most 
desirable  liquid  material  would  make  a  fairly  good  paint 
compared  to  reverse  conditions.  The  complex  functions, 

21 


careful  preparation  of,  and  extreme  sensitiveness  of  the 
liquids,  necessitate  a  knowledge  covering  a  much  wider 
field  of  experience. 

Moreover,  pigments  have  less  latitude  in  their  func- 
tions and  present  opportunities  of  physical  examination 
for  requirements  that  are  easily  and  finally  determined. 

Neither  heat  nor  cold  affects  pigments  to  any  unde- 
sirable extent, — graphite,  Venetian  red,  red  oxide,  yellow 
ochre,  umber  and  many  others  being  fire-proof  to  the 
extent  of  readily  withstanding  temperatures,  many 
times  higher  than  that  necessary  to  produce  a  red  heat 
on  steel.  They  are  also  acid  proof  to  the  extent  of 
not  being  affected  by  the  most  effective  acid  fumes  or 
gases  that  are  possible  in  open  atmospheres. 

Many  deceptions  on  this  point  are  practiced  upon 
the  public  by  dishonest  manufacturers,  who  claim  or 
infer  originality  in  that  they  have  a  fire  and  acid  proof 
pigment,  when  in  fact  the  majority  of  the  most  frequent- 
ly used  and  cheapest  materials  for  this  purpose  possess 
these  features. 

Deceptions  are  practiced  to  such  an  extent  with 
graphite  that  many  interested  persons  looking  forward 
to  the  purchase  of  paint  containing  graphite  as  a  pig- 
ment ask  the  question,  "  Where  do  you  get  your 
graphite?" 

This  deception  arises  from  the  fact  of  various  manu- 
facturers, convincing  prospective  purchasers  that  they 
own  or  control  graphite  mines  which  produce  graphite 
of  incomparable  purity,  or  peculiar  qualities  not  possi- 
ble with  any  other. 

It  will  be  seen  that  the  question  of  selecting  pig- 
ments that  will  withstand  heat,  cold,  and  acids  is  a 
simple  one,  and  that  the  white  and  colored  pigments 
contain  oxygen  which  when  combined  with  a  drying  oil 
hasten  more  or  less  the  oxidation  of  it,  and  that  no  risk 
whatever  may  be  run  in  the  selection  of  inert  pigments, 
such  as  graphite  or  lampblack  in  the  choice  of  the  best 
and  most  protective  mediums  to  be  mixed  with  oil  for  the 
production  of  the  most  effective  protective  coating  for 
metal  surfaces. 

The  liquids  used  in  paints  are  compound  substances. 
They  are  not  fixed  or  stable,  and  they  constitute  ve- 
hicles susceptible  to  .decomposition,  vitally  affecting  the 
durability  of  the  film  of  a  protective  coating  and  therein 
lies  room  for  constant  investigation  and  improvement. 

22 


Vehicles  are  those  liquids  which  are  used  with  pig- 
ments to  carry  them  in  a  fluid  form  for  convenient  ap- 
plication on  the  surface  for  which  it  is  intended. 

The  functions  which  vehicles  should  perform  in  pro- 
tective coatings  for  metal  should  be  that  they  should 
have  a  close  affinity  with  the  pigments  with  which  they 
are  mixed  and  form  a  dry,  waterproof  and  durable  non- 
porous  coating,  one  that  will  not  chemically  deteriorate 
the  metallic  surface  on  which  it  is  applied.  Certain  oils 
have  been  found  to  possess  the  greater  amount  of  these 
functions  and  those  oils  which  dry  on  a  surface  by  co- 
agulation due  to  oxidation  are  being  used  for  the  pur- 
pose. 

The  oils  which  dry  or  coagulate  by  oxidation  are 
not  numerous,  but  their  extraction,  purification  and  sub- 
sequent treatment  are  very  important,  demanding  a 
large  amount  of  technical  skill :  these  oils  are  more  or 
less  viscous  varying  considerably  with  the  process  and 
care  taken  in  their  preparation. 

The  value  of  an  oil  for  use  as  a  vehicle  depends  al- 
most entirely  upon  its  durability  when  dry :  thus  oils  may 
be  divided  into  two  classes,  the  fatty  oils,  and  the  vola- 
tile oils,  or  evaporating  oils. 

The  fatty  oils  are  greasy  and  are  incompatible  with 
water ;  when  oil  and  water  come  together  they  do  not 
mix,  (excepting  when  mixed  with  strong  acids  or  al- 
kalies) water  running  over  a  fatty  substance  does  not 
wet  its  surface.  This  property  is  therefore  useful  for 
oil  paints,  for  surfaces  coated  with  an  oil  paint  made  of 
fatty  oil  and  pigment  are  protected  from  the  destructive 
action  of  water. 

Those  fatty  oils  which  when  exposed  to  the  at- 
mosphere, after  being  spread  on  a  surface,  become  solid 
and  coagulate  into  a  varnish  like  coating,  are  known  as 
drying  oils  and  are  distinguishible  from  the  non-drying 
oils  in  that  the  latter  remains  either  fluid  or  greasy  for 
an  indefinite  period. 

Among  the  drying  oils  the  best  known  and  most 
commonly  used  are  linseed  oil,  poppy  oil  and  Chinese 
wood  oil.  Poppy  oil  and  Chinese  wood  oil,  however, 
are  not  only  too  expensive  to  use  for  the  manufacture 
of  protective  paints,  but  they  do  not  possess  sufficient 
durability  over  linseed  oil  to  warrant  the  excess  cost 
necessary  for  their  use.  All  other  drying  oils  either 

23 


dry  so  slowly  or  imperfectly  that  they  are  undesirable 
compared  to  linseed  oil. 

The  drying  power  of  oils  is  directly  proportional  to 
the  amount  of  oxygen  they  are  capable  of  absorbing,  and 
if  the  absortion  of  oxygen  is  not  checked  the  oil  becomes 
over  oxidized  and  loses  its  tenacity  and  cohesiveness. 

The  increase  of  drying  properties  of  linseed  oil  is 
accomplished  by  extracting  impurities  which  chiefly  con- 
sist of  cellular  tissue  and  albuminous  matter,  etc.  It  is 
usually  done  by  storing  the  oil  in  large  tanks  allowing 
the  impurities  to  settle  to  the  bottom  after  which  the  oil 
is  drawn  off,  leaving  the  sediment  behind.  The  oil  is 
then  clarified  by  passing  through  a  filter  press. 

To  further  increase  the  drying  properties  of  linseed 
oil  it  is  boiled  in  the  presence  of  manganese  dioxide, 
manganese  borate,  red  lead,  litharge  or  other  substances 
and  raised  to  a  temperature  high  enough  and  main- 
tained long  enough  to  impart  the  proper  requirements 
to  it.  The  treatment  of  linseed  oil  requires  such  a  great 
amount  of  skill  and  experience,  and  the  various  forms  of 
treating  the  same  are  so  many  that  the  study  of  it  for 
a  lifetime  would  develop  new  experiences  continuously. 
Therefore,  the  treatment  of  linseed  oil  will  not  be  dis- 
cussed at  length  here. 

When  linseed  oil  dries  it  is  called  "Linoxyn"  (Lin- 
seed oil  +  Oxygen)  for  the  reason  that  it  forms  a  perfect 
chemical  union  with  oxygen  and  is  th'en  converted  into 
the  solid  material  thus  named. 

Linseed  oil  expands  during  the  period  of  absorbing 
oxygen  until  it  becomes  thoroughly  dry,  after  which  the 
swelling  up  very  gradually  subsides.  The  expansion 
takes  place  to  such  a  great  extent  that  it  is  not  only 
readily  perceptable  by  appearance,  but  a  difference  in 
weight  can  be  easily  ascertained  owing  to  the  very  large 
proportion  of  oxygen  consumed  in  the  process. 

Almost  any  one  familiar  with  linseed  oil  knows  that 
after  the  drippings  from  a  linseed  oil  can  falls  onto  a 
piece  of  glass  or  other  non-porous  surface,  it  begins  to 
thicken  as  it  dries. 

The  formation  of  a  paint  or  oil  skin  on  the  top  of 
liquid  linseed  oil  paint  exposed  to  the  atmosphere  is  thus 
easily  accounted  for  as  being  a  formation  of  linoxyn.  It 
will  be  noticed  furthermore  that  a  linseed  oil  paint  skin 
becomes  crinkled  on  the  top,  and  this  is  due  to  the  ab- 
sorption of  more  oxygen  on  the  surface  where  contact 

24 


is  had  with  atmospheric  oxygen,  than  can  be  ad- 
mitted farther  below  the  surface  thereby  causing  ex- 
pansion on  the  top  greater  than  the  wet  side  of  the  skin 
which  lies  underneath.  Gradually  the  paint  skin  admits 
more  oxygen  until  the  linoxyn  gets  thick  enough  to  re- 
tard the  progress  of  absorption,  and  reaches  a  point 
where  it  seems  to  cease. 

It  will  be  seen  that  pigments  mixed  with  linseed  oil 
cut  down  the  percentage  of  linseed  oil  in  proportion  to 
its  bulk,  for  the  formation  of  linoxyn,  and  the  subsequent 
clogging  of  the  pores  in  the  linoxyn  by  the  pigment 
(which,  if  graphite,  does  it  to  >a  greater  degree  than  the 
coarser  pigments)  renders  the  linoxyn  for  a  limited  time 
less  porous  than  if  the  oil  were  not  combined  with  the 
pigment;  provided,  however,  that  not  more  pigment  be 
used  than  the  oil  will  properly  envelop  and  carry  with 
it. 

It  will  be  noticed,  moreover,  that  a  fresh  dried  lin- 
seed oil  paint  film  (without  a  volatile  oil  admixture)  is 
thicker  than  when  the  coating  was  in  the  wet  state.  This 
causes  the  oil  to  expand  and  protrude  above  the  pigment, 
thus  exposing  the  protruding  oil  to  direct  attack  of  dis- 
intregating  influences,  while  protecting  the  pigment  at 
the  same  time.  Shortly  after  the  linseed  oil  becomes 
dry  and  reaches  its  fullest  extent  of  expansion  it  begins 
to  subside  and  to  lose  its  gloss,  on  account  of  becoming 
porous,  and  also  for  the  fact  that  it  becomes  excessively 
oxidized  and  worn  down  to  the  pigment ;  at  this  stage 
oxidation  and  disintegration  of  the  vehicle  is  retarded  or 
accelerated  according  to  the  nature  of  the  pigment,  which 
if  carbon  accomplishes  the  former,  and  if  oxygen  pig- 
ments the  latter.  Hence,  it  will  be  seen  that  the  organic 
matter  of  a  paint  which  is  the  vehicle,  is  the  unstable 
and  highly  sensitive  portion  of  it  that  requires  the  most 
important  and  careful  treatment. 

The  volatile  oils  used  in  paints  are  those  generally 
called  terpenes  in  chemistry.  They  usually  belong  to 
one  of  the  groups  of  hydrocarbons  having  the  same  or  a 
similar  composition  as  turpentine  (Ci0H16),  they  are 
highly  inflammable  and  when  dropped  upon  a  sheet  of 
glass  and  exposed  to  the  atmosphere  for  a  short  time 
completely  evaporate.  The  function  of  a  volatile  oil  in 
paint  is  either  to  adulterate  the  linseed  oil,  lessen  the 
viscosity  of  the  paint,  cause  the  paint  to  flow  more  freely 
so  that  a  thin  and  consequently  quick  drying  paint  will 

25 


ensue,  or  for  the  purpose  of  dissolving  gum  resins  so  as 
to  make  a  quick  drying  varnish,  sometimes  used  as,  (and 
erroneously  called)  a  dryer.  In  this  case  the  volatile 
oil  evaporates  from  the  resin  leaving  a  thin  coating  or 
deposit  of  the  resin  of  the  same  character  practically  as 
it  was  before  being  dissolved  into  the  volatile  oil. 

The  volatile  oils  usually  employed  are  benzine,  petro- 
leum naphtha,  coal  tar  naphtha  (sometimes  called  creosote 
oil),  benzole  and  turpentine.  When  these  are  used  to 
any  extent  in  linseed  oil,  paint  not  having  a  solid  com- 
position in  solution  with  the  oil,  the  paint  loses  consider- 
able of  its  value.  The  pigment  will  separate  from  the 
oil  freely  and  precipitate  to  the  bottom  soon  after  being 
mixed  with  the  oil,  the  viscosity  and  adhesiveness  of  the 
paint  would  be  impaired,  the  coating  would  be  too  thin 
to  give  ample  protection  and  porosity  would  result  imme- 
diately after  the  evaporation  of  the  volatile  oil  from  the 
painted  surface,  thus  defeating  the  very  object  of  a  pro- 
tective coating  and  rendering  the  coagulated  mass  of 
dried  paint  less  efficient  and  durable. 

Metal  surfaces  defy  the  absorption  of  paint  to  such  a 
deg'ree  that  the  admixture  of  a  thin  or  volatile  oil  for  the 
purpose  of  creating  a  penetrating  paint  is  useless.  Hence, 
the  lack  of  necessity  of  using  a  thin  priming  coat,  which, 
if  used,  would  run  down  in  streaks  on  a  vertical  or  in- 
clined surface. 

On  the  other  hand,  should  the  paint  be  made  quite 
thick  by  the  use  of  the  pigment  it  will  be  done  at  the 
expense  of  the  vehicle  and  its  adhesiveness,  as  there  will 
not  be  sufficient  vehicle  to  carry  the  pigment  over  the 
surface  to  be  painted,  and  leave  a  glossy  oily  finish. 

Protective  coatings  for  metal  should  be  heavy  bodied 
by  the  use  of  a  heavy  bodied  vehicle  and  should  be  sticky 
enough  in  the  liquid  state  to  take  to  the  metal  freely 
from  the  brush.  It  should  be  capable  of  being  brushed 
out  thin  or  flowed  on  thick  before  it  has  time  to  set  and 
should  not  run  on  a  vertical  surface  when  thus  applied. 

It  should  be  quick  setting  but  slow  drying ;  the  former 
to  withstand  unexpected  rain  storms  shortly  after  appli- 
cation, and  the  latter  to  prevent  premature  hardening  to 
a  state  of  brittleness,  not  consistant  with  sufficient  ex- 
pansion and  contraction  of  the  metallic  surface  due  to 
extreme  changes  of  temperature,  which  on  a  dry  paint 
film  averaging  one  two  hundredth  of  an  inch  in  thickness, 
would  not  be  inconsiderable. 

26 


:«iVER3ITY   ) 

J 

.c4LlFORN\fe/ 


Soluble  solids,  as  their  name  implies,  are  those  solid 
materials  which,  when  melted  into  a  liquid  state,  are 
capable  of  being  dissolved  into  the  oils  for  the  purpose  of 
creating  a  compound  vehicle  or  a  varnish. 

Varnish  gums  are  soluble  solids  and  so  are  tars, 
pitches,  asphaltums  and  also  prepared  compositions  made 
for  the  purpose;  all  of  which  have  various  and  diverse 
qualifications  for  use  in  paints  and  varnishes  for  specific 
purposes,  and  a  knowledge  of  their  characteristics  are 
necessary  in  order  to  select  the  proper  ones  for  their  ade- 
quate use. 

The  functions  of  soluble  solids,  in  protective  linseed 
oil  paints,  are  to  impart  to  the  oil  quick  setting,  adhesive 
elastic  properties,  viscosity  and  durability  by  way  of 
protecting  the  linoxyn  from  over  oxidation,  and  that 
state  which  is  commonly  called  the  "  chalking  off  "  condi- 
tion of  the  pigment  in  the  dry  paint  in  which  state  it 
reaches  the  point  where  it  has  ceased  to  be  a  protective 
coating.  The  prolongation  of  the  protective  qualities  of 
an  oil  by  the  use  of  a  soluble  solid  depends  entirely  upon 
the  character  of  exposure,  together  with  the  proper 
amount  of,  and  character  of,  the  soluble  solid  to  be  used 
in  the  oil,  and  also  the  quality  of  the  oil  to  be  used.  The 
boiling  down  of  linseed  oil  to  a  thick  sticky  consistency 
does  not  take  the  place  of  the  proper  sort  of  soluble 
solid,  for  the  reason  that  it  will  not  "  take  to  "  a  suf- 
ficient quantity  of  pigment,  neither  will  it  allow  of  the 
production  of  free  and  easy  spreading  qualities.  Further- 
more, the  oil  thus  treated  does  not  delay  excess  oxidation, 
which  is  the  feature  most  desired. 

The  progress  of  oxidation  of  linseed  oil  paints,  not 
having  a  soluble  solid,  may  easily  be  noticed  after  fre- 
quent rain-storms,  dews  or  other  forms  of  moisture  have 
become  evaporated  soon  after  contact  with  the  dried 
paint  (similar  to  the  action  necessary  to  rapidly  produce 
rust.) 

The  paint  loses  its  gloss,  becomes  dried  out  eventu- 
ally ;  so  that  the  only  perceptible  part  of  the  paint  which 
is  left  is  the  pigment.  All  of  these  characteristics  develop 
to  a  degree,  proportionate  to  the  frequency  with  which 
the  applications  of  moisture  on  the  surface  and  its  com- 
plete evaporation  therefrom  has  been  accomplished. 

A  soluble  solid  to  counteract  these  defects  should  be 
insoluble  in  water,  but  soluble  in  linseed  oil,  it  should 
be  solid  yet  elastic  in  its  basic  state  and  maintain  this 

27 


condition  without  perceptible  change;  withstanding  as 
large  a  variation  of  temperature  as  possible,  it  should 
not  absorb  oxygen  nor  become  perceptibly  effected  by  it, 
and  when  dissolved  into  the  oil  should  form  a  compound 
vehicle  which  will  effectively  combat  the  attack  of  water, 
heat,  cold,  oxygen,  sulphurated  hydrogen  gas,  carbon- 
dioxide  gas,  and  to  a  great  extent  the  effects  of  the 
oxide  pigments  when  the  same,  of  necessity,  have  to 
be  used.  It  should  not  impair  the  proper  drying  quali- 
fications of  the  oil;  that  is  not  allow  the  coating  to  re- 
main tacky  or  sticky  for  a  long  time  after  it  is  applied, 
and  when  necessity  requires  it,  it  should  allow  of  suf- 
ficient volatile  oil  in  combination  to  allow  the  paint  to 
spread  freely  and  set  tough  enough  in  a  few  hours  to 
withstand  the  deleterious  effect  of  unexpected  rainfalls, 
and  possess  an  amount  of  cohesiveness  that  the  viscous 
mass  of  solid  soluble  material  will  flow  together  while 
the  evaporation  of  the  volatile  oil  takes  place,  leaving  the 
surface  tough,  elastic,  smooth  and  waterproof,  thus  elim- 
inating the  defects  possessed  by  all  of  the  straight  oil 
paints  where  volatile  oils  are  used. 

The  proper  use  of  a  soluble  solid  in  linseed  oil  paints 
intended  to  prolong  the  life  of  a  protective  coating  for 
metal  has  heretofore  been  but  very  feebly  attempted  by 
paint  manufacturers.  Rosin  and  some  of  the  black 
pitches  are  often  used,  and  these  are  used  mostly  as 
adulterants,  or  to  add  a  temporary  glossy  appearance  at 
the  expense  of  the  durability  of  the  paint  which  con- 
tains it. 

There  has  been  little  or  no  demand  for  the  use  of 
soluble  solids  in  the  composition  of  oil  paints  for  the 
reason  that  the  public  has  not  known  the  benefits  to  be 
derived  from  the  use  of  it.  The  extra  cost  necessary  for 
its  addition  to  paint,  together  with  the  difficulty  of  ob- 
taining one  possessing  the  requisite  physical  and  chemi- 
cal requirements  which  can  only  be  ascertained  after 
exhaustive  and  tedious  tests  covering  years  of  experi- 
menting, have  induced  manufacturers  of  protective  coat- 
ings to  abandon  this  feature  in  the  composition  of  their 
products,  and  as  a  result  almost  all  of  the  protective 
coatings  now  on  the  market  with  any  claims  to  being 
high  grade  are  straight  oil  paints  with  the  omission  of 
SL  soluble  solid  in  their  composition. 

Those  paints  which  are  not  of  recognized  standard  as 

28 


being  high  grade  often  have  rosin,  pitch  or  a  cheap  rosin 
dryer  in  their  composition. 

The  writer  has  been  confronted  with  these  facts  for 
many  years,  and  after  an  exhaustive  system  of  experi- 
ments has  succeeded  in  converting  by  a  chemical  phe- 
nomena in  the  use.  of  chlorine  gas,  an  oil  of  vegetable 
origin  which  has  no  drying  or  oxidizing  properties,  into 
a  solid  rubber-like  mass  of  a  light  yellow  color,  complete- 
ly converting  the  vegetable  grease  or  fatty  matter  into 
a  new  substance,  which,  when  melted  (necessitating  a 
heat  of  600  degrees  F.)  turns  black,  flows  like  oil  and 
is  perfectly  soluble  in  boiling  linseed  oil,  becoming  part 
of  the  vehicle  itself  and  incapable  of  mechanical  separa- 
tion therefrom. 

This  soluble  solid  composition  has  in  the  past  five 
years  proven  to  be  the  missing  link  needed  to  produce 
a  protective  coating  of  the  highest  efficiency  in  every  re- 
spect, and  it  is  with  pleasure  to  the  writer  that  a  pro- 
tective coating  with  over  twice  the  durability  of  anything 
yet  produced  for  a  top  coat,  of  the  highest  efficiency  is 
now  produced  and  offered  to  those  who  are  interested 
enough  in  this  subject  to  demand  it  for  their  use. 

The  writer  has  become  acquainted  with  paints  that 
were  represented  to  contain  rubber  (caoutchouc)  and  has 
personally  made  paints  with  this  material.  Manufactur- 
ers of  so  called  "  rubber  paints  "  claim  that  the  rubber 
contained  in  their  paints  make  the  paints  more  adhesive 
and  elastic,  thereby  extending  the  life  of  the  paint,  by 
reason  of  its  lessened  liability  to  become  hard  and  brittle 
and  eventually  crack. 

The  extreme  high  price  of  rubber,  notwithstanding 
the  small  amount  needed  on  account  of  its  property  of 
swelling  up  considerably  in  the  oils  into  which  it  may 
become  dissolved,  makes  its  use  in  paint  prohibitory,  fur- 
thermore as  a  paint  material  it  is  worthless. 

The  author,  as  well  as  all  manufacturers  of  rubber 
goods,  know  that  oxidizing  oils,  or  oils  used  in  the  manu- 
facture of  paint,  will  rot  the  rubber  shortly  after  ex- 
posure to  the  weather,  and  when  it  has  become  dry  on  a 
surface  its  shrinkage  opens  up  large  crevices  and  the 
balance  of  it  becomes  crumbly,  resembling  a  condition  of 
dry  rot.  These  circumstances  clearly  demonstrate  that 
rubber  has  absolutely  no  value  in  paint  and  that  the  use 
of  it  in  this  respect  not  only  entails  a  useless  expendi- 
ture of  money  incidental  to  its  cost,  but  also  the  cost  of 

29 


applying  a  paint  containing  materials  which  tend  to  cur- 
tail its  efficiency. 

In  all  cases  investigated,  however,  the  manufacturers' 
claim  to  using  rubber,  either  new  or  old,  in  painvr  has 
proven  to  be  a  deception  in  order  to  obtain  a  high  price 
for  a  coal  tar  product,  or  one  no  more  costly  in  its  pro- 
duction than  one  of  this  sort. 

We  have  noted  in  the  foregoing  pages  the  functions 
of  pigments,  vehicles  and  volatile  oils,  and  it  will  be  ob- 
served that  their  action,  while  in  combination  as  a  pro- 
tective coating,  is  more  or  less  definitely  understood. 
Not  so,  however,  with  suitable  soluble  solids,  for  as 
stated,  none  but  deleterious  hard  brittle  rosins,  tars  or 
pitches  (or  if  they  are  not  hard  and  brittle  to  start  with 
they  soon  get  that  way  under  exposure)  have  been  used 
and  the  author  has  no  hesitancy  in  saying  that  he  who 
solves  the  problem  of  intelligently  compounding  a  solu- 
ble solid  composition  that  will  definitely  double  the  life 
of  linseed  oil  as  a  vehicle  in  protective  coatings  without 
increasing  its  cost,  unlocks  some  of  the  secrets  of  chem- 
istry, which,  without  doubt,  is  an  acquisition  of  no  slight 
value. 


Chapter  V. 

VARNISHES. 

Their  Bases  and  Characteristics. 

The  line  of  demarkation  as  to  what  constitutes  a  var- 
nish for  a  paint  has  been  more  or  less  confused  where  the 
varnish  is  not  transparent  and  where  the  paint  has  a 
varnish  vehicle.  In  order  to  avoid  confusion  we  shall  de- 
fine a  varnish  as  a  liquid  substance,  not  containing  a 
pigment,  which  is  capable  of  drying  on  a  surface  over 
which  it  has  been  diffused  to  beautify  or  protect  the 
same. 

A  varnish  may  consist  of  a  drying  oil,  a  drying  oil 
with  a  soluble  solid  base,  or  a  volatile  oil  with  a  soluble 
solid  base  or  the  combination  of  any  or  all  of  these  into 
one. 

The  drying  oils  we  have  mentioned  on  page  2.'i,  some 
of  the  soluble  solid  bases  for  varnishes  are  those  men- 
tioned on  page  27,  and  the  volatile  oils  used  are  tho'se 
mentioned  on  page  20. 

Varnishes  may  be  either  transparent  or  opaque,  and, 
when  the  latter,  they  are  generally .  black,  such  as  tar 
varnish  or  asphaltum  varnish,  &c.  The  transparent  var- 
nish bases  consist  of  common  rosin,  which  is  the  residue 
left  in  the  stills  after  the  distillation  of  turpentine,  or 
resins,  originating  by  their  exudation  from  various  spe- 
cies of  trees,  some  of  which  have  disappeared  centuries 
ago,  leaving  the  resins  embedded  in  the  soil,  and  include 
mastic  dammar,  Sandarac,  copal,  kauri,  and  many  others, 
all  of  which  contain  carbon,  hydrogen  and  oxygen,  and 
are  very  brittle  at  ordinary  atmospheric  temperatures 
and  melt  at  temperatures  ranging  from  200  to  500  degrees 
F. 

When  they  are  combined  with  linseed  oil  or  linseed 
oil  paints  they  impart  considerable  viscosity  and  adhe- 
siveness to  the  paint  while  in  the  liquid  state,  and  when 
the  paint  becomes  dry  higher  gloss  and  better  finish,  but 
after  prolonged  exposure  to  the  atmosphere  on  a  large 
metal  surface  subjected  to  considerable  heat  from  the 
sun's  rays,  where  rapid  radiation  of  the  heat  and  sudden 
cooling  off  of  the  metal  causes  considerable  contraction 

31 


and  expansion  to  take  place;  the  paint  rapidly  becomes 
badly  cracked  and  loses  its  adhesiveness. 

The  increased  viscosity  and  adhesiveness  of  the  liquid 
paint  is  not  only  lost  in  the  dried  paint,  but  it  rapidly 
becomes  very  hard  and  brittle.  This  brittleness  is  due 
to  the  evaporation  of  the  volatile  matter  in  the  paint  or 
the  excess  oxidation  of  linseed  oil  in  which  a  brittle  solu- 
ble substance  has  very  little  lasting  effect. 

Pigments  in  combination  with  a  resin  or  pitch  tend  to 
excessively  harden  them  when  they  have  become  dry,  and 
thus  it  will  be  seen  that  the  separation^  of  a  pigment  from 
a  resin  or  pitch  varnish  is  an  advantage  where  great 
variations  of  temperatures  are  to  be  met  with. 

The  pitches  which  are  used  in  many  of  the  so-called 
protective  coating  are  coal  tar  pitch,  asphaltum  pitch  and 
petroleum  pitch,  &c.,  and  these  go  under  so  many  differ- 
ent names,  in  order  to  hide  their  indentity  from  pur- 
chasers that  it  would  be  impossible  to  keep  track  of  the 
new  names,  which  are  invented  to  deceive  the  unwary. 

These  pitches  have  to  be  made  into  very  hard  brittle 
substances  by  cooking  them  in  kettles  before  adding  the 
oils,  otherwise  their  foundation  as  a  base  would  not  be 
solid  enough  to  allow  the  substance  to  harden  on  a  sur- 
face and  become  dry. 

When  pigments  are  added  to  a  soft  pitch  with  a  view 
to  causing  them  to  dry  it  not  only  augments  the  lack  of 
toughness,  but  serves  to  detract  the  stickiness  from  the 
pitch,  for  the  reason  that  pigment  alone  has  no  viscosity, 
being  a  dry  substance.  Therefore  when  pitches  are  to  be 
used  they  should  be  used  in  varnishes  only,  if  they  are  to 
impart  their  full  value  to  a  coating  intended  for  protect- 
ive purposes. 

The  melting  point  of  a  pitch  or  resin  is  the  degree  of 
temperature  necessary  to  maintain  it  in  a  molten  state, 
and  the  brittle  point  is  the  degree  of  temperature  neces- 
sary to  cause  it  to  harden  into  a  brittle  state,  which 
state  can  be  noted  by  striking  it  with  a  hammer. 

Almost  all  of  the  different  pitches  have  a  different 
melting  point,  and  one  that  softens  while  in  combination 
with  paint  materials  during  exposure  to  atmospheric 
temperatures,  and  will  correspondingly  harden  to  a  state 
of  brittleness  when  the  temperature  lowers  is  sure  to 
crawl  and  crack  on  the  surface.  These  cracks  form  in 
transverse  directions,  forming  a  defective  surface,  which 
is  known  as  being  "  alligatored,"  resembling  in  shape  the 

32 


peculiar  formations  on  the  surface  of  an  alligator  skin. 

When  an  "  alligatored  "  surface  forms  and  continued 
contraction  and  expansion  of  the  metal  ensues  the  edges 
of  the  alligatored  scales  will  finally  curl  up,  "  letting  go  " 
of  the  metal  entirely,  thus  allowing  moisture  and  dust  to 
get  underneath  them,  facilitating  the  process  of  ridding 
the  surface  of  the  paint  and  promoting  active  rust  forma- 
tions. 

The  melting  point  of  a  pitch  or  resin  may  easily  be 
ascertained  by  placing  the  same  in  a  small  iron  cup,  into 
which  the  bulb  of  a  thermometer  has  been  inserted,  and 
noting  the  results  after  heat  has  been  applied  to  the 
bottom  of  the  cup. 

Most  of  us  know,  however,  that  'atmospheric  heat  on 
a  warm  day  will  soften  coal  tar  pitch  to  such  an  extent 
that  it  will  run  on  a  surface  or  may  be  pulled  out  into 
long  strings  and  after  cooling  it  by  dipping  it  into  a  basin 
of  cold  water  it  will  fly  into  small  pieces  or  may  be 
finely  pulverized  by  a  simple  blow  from  a  hammer.  This 
once  soft  and  afterward  brittle  condition  will  be  noticed 
where  paints  or  varnishes  containing  these  pitches  are 
exposed  on  a  surface  at  atmospheric  temperatures,  pro- 
vided, however,  that  the  same  has  been  applied  on  the 
surface  heavy  enough  to  obtain  from  them  their  maxi- 
mum amount  of  wear. 

In  proportion  to  its  bulk  it  requires  a  large  amount 
of  volatile  oil  to  reduce  a  resin,  tar  or  pitch  to  a  liquid 
condition  thin  enough  to  be  capable  of  proper  spreading 
properties,  with  a  paint  brush,  at  a  temperature  of  60 
degrees  F.  Hence  a  very  thin  deposit  of  the  solid  base 
of  the  mixture  will  be  left  upon  the  surface  after  the 
volatile  oil  has  evaporated.  If  extreme  care  is  not  taken 
in  brushing  it  on  thick  enough  to  allow  for  the  evapora- 
tion of  the  volatile  oil  and  leave  a  substantial  coating, 
lack  of  durability  will  be  inevitable,  for  the  coating 
which  will  remain  on  'the  surface  will  be  so  thin  or 
badly  disintegrated  by  the  solvent  action  of  the  oil  first. 
and  its  evaporation  afterwards,  that  its  adhesion  to  the 
surface  will  be  a  matter  of  only  a  few  months,  or  even 
weeks,  when  subjected  to  atmospheric  exposure,  and 
soon  afterwards  no  trace  of  it  is  liable  to  be  seen  what- 
ever. On  the  other  hand,  should  it  be  spread  on  too 
thick,  a  badly  alligatored  surface  will  result  These  are 
the  reasons  why  tar  and  asphaltum  varnishes  are  so  un- 
reliable on  tin  roofs,  and  the  author  knows  of  no  way 

33 


in  which  they  may  be  made  reliable  in  a  practicable  way 
so  that  any  one  who  knows  how  to  spread  paint  can  have 
some  sort  of  definite  assurance  that  it  is  going  to  last 
two  years  at  least  For,  as  explained,  the  thickness  of 
the  coating  has  considerable  to  do  with  it,  and  as  the 
volatile  oil  evaporates  so  quickly,  and  indefinately  in 
varying  temperatures,  lack  of  uniformity  of  the  deposit 
left  upon  the  surface  is  sure  to  ensue.  In  fact,  the  author 
knows  of  hundreds  of  instances  where  a  tar  varnish 
applied  to  a  tin  roof  would  last  four  years,  and  be  alli- 
gatored,  and  part  of  the  same  varnish  taken  from  the 
same  barrel  and  applied  by  the  same  painter  the  follow- 
ing day  on  an  adjoining  roof  of  the  same  conditions  of 
surface  would  dry  out  and  wash  off  within  a  year.  More- 
over, weather  conditions  and  temperatures  render  the 
prevention  of  these  defects  of  a  highly  volatile  varnish 
impossible. 

Rosin  more  readily  impairs  the  stability  of  a  coating 
into  which  it  has  entered  than  any  of  the  other  resins, 
and  every  ounce  of  it  combined  with  a  gallon  of  paint 
can  be  noticed  to  detract  from  its  wearing  qualities. 

Many  of  the  so-called  paint  dryers  on  the  market  are 
nothing  more  or  less  than  a  thin  rosin  varnish,  and  in 
consequence  should  be  avoided.  If,  however,  a  dryer  is 
absolutely  needed,  only  oil  dryers  with  thickening  or 
oxygen  absorbing  properties  should  be  used,  and  then 
only  in  minimum  quantities,  necessary  to  meet  unavoid- 
able requirements. 


34 


Chapter  VI. 

Diagnosing  Conditions  of  Exposure. 

This  is  an  important  matter  in  the  selection  of  the 
most  suitable  paint  for  a  purpose. 

Plate  II  shows  a  smokestack  below  the  roof  in  a  sheet 


Plate  II. 

mill.     The  paint  was  made  by  one  of  the  most  reputable 
manufacturers  in  the  country,  and  was  compounded  of 

35 


high-grade  raw  materials.  The  manufacturer  guaranteed 
it  to  last  one  year  on  this  stack,  which  did  not  get  over 
700  degrees  F.  The  condition  of  the  paint,  as  shown  in 
the  illustration,  became  so  one  week  after  it  was  applied 
and  thoroughly  dry.  Paint  taken  from  the  same  mix  in 
the  barrel  was  applied  on  a  tin  roof  in  the  neighborhood 
the  same  day,  and  five  years  afterward  was  in  perfect 
condition, -thus  illustrating  the  proper  use  for  that  par- 
ticular kind  of  paint.  On  the  other  hand,  a  cheaper  and 
differently  made  paint  was  applied  to  this  stack  a  few 
days  later,  after  the  scales  were  cleaned  off,  and  it  stood 
the  exposure  fairly  well  for  one  year,  and  on  a  tin  roof 
in  the  neighborhood  it  did  not  preserve  the  metal  over 
four  months. 

Samples,  which  are  occasionally  painted  on  small 
pieces  of  tin  and  sent  out  by  the  manufacturers  to  bend 
and  twist,  appear  all  right  until  they  have  been  exposed 
to  the  weather  for  a  year  or  so  at  which  time  their  beau- 
tiful appearance  and  preserving  qualities  have  quite  van- 
ished. 

In  order  to  select  a  protective  coating  to  the  best  pos- 
sible advantage  the  conditions  of  exposure  should  be  thor- 
oughly understood  first ;  other  conditions,  such  as  the 
character  of  the  surface,  and  number  of  coats  to  apply 
should  follow. 

The  exposure  of  dry  paint  surfaces  may  be  conveni- 
ently divided  into  eight  classes  as  follows: 

1.  Ordinary  interior  exposures. 

2.  Ordinary  exterior  exposures. 

3.  Extraordinary  interior  exposures. 

4.  Extraordinary  exterior  exposures. 

5.  Extraordinary  exposure  to  heat  (other  than  atmos- 
pheric). 

6.  Extraordinary  exposure  to  cold  (other  than  atmos- 
pheric). 

7.  Extraordinary  exposure  to  liquids   (other  than  at- 
mospheric) . 

8.  Extraordinary  exposure  to  abrasion  (other  than  at- 
mospheric). 

No.  1.  Ordinary  interior  exposure  rarely  covers  a  va- 
riation of  temperature  of  more  than  60  degrees  F.,  conse- 
quently the  expansion  and  contraction  of  the  surface  met 
with  in  this  class  of  exposure  is  so  small  that  it  has  very 
little  effect  upon  an  ordinary  paint  properly  put  on  and 
of  good  materials,  neither  does  moisture  and  its  rapid 

36 


evaporation  prevail,  so  that  here  we  have  a  condition 
notable  for  its  simplicity.  Take,  for  instance,  several 
small  sheets  of  tin  or  iron  with  clean,  bright,  dry  sur- 
face, coat  them  with  coal  tar  varnish,  asphaltum  var- 
nish, or,  in  fact,  any  cheap  paint,  and  when  thoroughly 
dry  lay  them  aside  in  the  drawer  of  a  writing  desk ;  20 
years  later  they  will  be  in  as  good  condition  as  the  day 
they  were  stored  away.  The  sheets  of  metal,  even  with- 
out paint,  laid  away,  in  like  manner  for  the  same  length 
of  time,  will  also  be  found  to  be  in  excellent  condition. 
Structural  iron  work  imbedded  in  cement  or  concrete  or 
otherwise  incased  should  have  one  coat  of  paint  applied 
at  the  shop  and  two  coats  afterward,  for  the  reason  that 
subsequent  coats  cannot  be  applied  after  the  building  is 
completed,  and  once  painted  it  is  expected  to  remain  so 
as  long  as  the  building  lasts.  Cement  and  concrete,  more- 
over, are  more  or  less  porous  and  draw  dampness  to  the 
metal. 

No.  2.  Ordinary  exterior  exposure  meets  with  climatic 
conditions  varying  over  125  degrees  F.,  ranging  from  the 
chilly  blasts  of  cold  weather  to  the  scorching  rays  of  the 
sun.  Here  expansion  and  contraction  holds  full  sway, 
tugging  and  straining  at  the  adhesive  and  elastic  prop- 
erties of  the  paint  while  adhering  to  a  surface  not  suc- 
ceptible  to  paint  absorption. 

Hail,  snow  and  ice,  thawing  and  freezing,  rain  and  its 
evaporation  attack  vigorously  the  organic  properties  of 
the  vehicle  in  a  paint.  When  a  varnish  is  used  to  with- 
stand this  class  of  exposure  the  heat  from  the  sun  con- 
tinues to  liberate  what  volatile  matter  it  contains  until 
it  becomes  baked  so  hard  and  brittle  that  its  adhesive- 
ness subsequently  becomes  a  matter  of  only  "  here  and 
there."  If  the  varnish  is  a  thick  coating  it  is  sure  to  be- 
come alligatored  when  the  metal  expands  and  contracts 
while  in  the  hard  condition,  and  if  it  is  a  thin  coating 
it  will  become  reduced  to  powder  and  wash  off.  This 
sort  of  exposure  requires  a  paint  of  superior,  elastic,  ad- 
hesive, oxygen  and  water  resisting  properties,  and  as  the 
top  coat  is  the  one  subject  the  most  of  all  to  these  condi- 
tions it  should  of  necessity  be  made  of  carefully  treated 
linseed  oil,  .graphite  and  a  suitable  soluble  solid  composi- 
tion to  protect  the  oil  so  as  to  add  permanence  to  the 
vehicle  as  explained.  The  reason  for  using  graphite  for 
the  pigment  is  explained  on  page  22. 

The  class  of  steel  work  generally  coming  under  this 

37 


class  of  exposure  is  bridges,  ornamental  ironwork,  fences, 
fire  escapes,  gutters,  valleys,  spouting,  roofing,  siding, 
towers,  sheathing  and  shutters,  &c.  New  materials  of  this 
class  should  receive  at  least  one  coat  of  paint  at  the  works 
and  one  coat  after  it  is  put  up. 

No.  3.  Extraordinary  interior  exposure,  such  as  will 
be  met  in  damp  cellars,  livery  stable  roofs  (exposed  on 
the  under  side  to  ammonia  fumes),  cast  house  roofs  at 
furnace  and  foundries  subjected  to  steam  and  heat,  under 
side  of  roofs  of  steel  mills  directly  over  sulphuric  acid, 
pickling  vats,  pulp  mills,  paper  mills  and  ships'  holds 
which  sweat  continuously,  &c.,  have  considerable  effect 
upon  the  paint  on  the  surface  and  paint  thus  exposed 
should  dry  harder  and  have  more  soluble  solid  in  its  com- 
position than  class  No.  2 :  two  good  coats  of  the  most 
suitable  paint  for  this  class  of  work  are  in  most  cases 
most  satisfactory,  and  when  the  top  coat  loses  its  effi- 
ciency it  should  be  replaced  with  another  one  before  ac- 
cess to  the  metal  is  gained,  as  this  will  save  considerable 
labor  in  removing  rust  which  would  otherwise  form. 

No.  4.  Extraordinary  exterior  exposure  are  those  ex- 
posures where  the  atmosphere  is  surcharged  with  acid 
fumes,  which  generally  emanate  from  open  coke  ovens, 
chimneys,  locomotive  stacks  and  chemical  works,  &c.  The 
effects  of  this  class  of  exposure  varies  extensively,  a 
great  deal  depending  on  the  distance  from  where  the 
fumes  emanate  and  the  character  of  them.  Painted  metal 
work  of  all  kinds,  especially  roofs  and  bridges,  in  the 
vicinity  of  these  quickly  lose  their  protective  coating  if 
the  paint  is  not  made  of  the  proper  materials  to  with- 
stand the  exposure.  Like  class  No.  2,  this  exposure 
necessitates  the  use  of  a  protective  coating  capable  of 
withstanding  considerable  expansion  and  contraction,  and 
should  not  harden  so  much  as  the  paint  needed  for  class 
No.  3.  It  must  furthermore  have  a  vehicle  protected  by  a 
soluble  solid  composition  properly  prepared  to  stand  the 
surcharged  atmosphere ;  and  an  inert  pigment,  such  as 
graphite,  white  lead  and  red  lead  pigments,  especially  are 
to  be  avoided  in  this  class.  If  this  form  of  exposure  is 
very  severe  three  coats  of  paint  should  be  used  on  the 
metal  work. 

No.  5.  Extraordinary  exposure  to  heat  takes  in  those 
conditions  where  heat  is  produced  by  artificial  means 
greater  than  atmospheric  heat,  and  comes  into  direct 
contact  with  the  painted  surface.  This  heat  may  come 

38 


in  contact  with  paint  exposed  to  outside  atmospheres,  or 
it  may  come  in  contact  with  paint  exposed  to  inside  at- 
mospheres. The  class  of  materials  subject  to  the  former 
consists  of  smokestacks,  blast  furnace  stoves  and  locomo- 
tive front  ends,  &c.,  and  those  subject  to  the  latter  con- 
sists of  boiler  fronts,  furnace  fronts  and  hot  air  and 
steam  pipes.  In  all  cases  corning  under  this  class  the 
maximum  amount  of  temperature  should  be  ascertained, 


Plate  III. 

and  if  found  to  be  more  than  the  boiling  point  of  water 
(212  degrees  F.)  a  compound  vehicle  will  be  necessary. 
As  explained  on  page  21,  ordinary  pigments,  such  as 
graphite,  Venetian  red,  yellow  ochre,  or  umber,  are  prac- 
tically fireproof,  consequently  the  fact  remains  that  the 
heat  resisting  properties  of  a  paint  is  equal  to  the  amount 
ot"  heat  which  the  vehicle  will  stand.  Should  the  heat  run 


39 


•>.-'    IKE 

4<VERSITY 


over  600  degrees  F.  little  or  no  linseed  oil  should  be  used, 
and  a  soluble  solid  composition  of  a  melting  point  a  few 
degrees  higher  than  the  hot  surface  must  necessarily  be 
expected  to  be  used  for  any  permanence  in  this  respect. 

In  1902  officials  of  The  American  Sheet  Steel  Com- 
pany called  upon  the  author  to  make  several  tests  per- 
sonally on  the  hot  smoke  stacks  over  their  pair  furnaces 
and  slab  mills,  stating  that  the  paint  when  selected  and 
bought  would  have  to  be  applied  to  the  stacks  while  hot. 
for  the  reason  that  the  furnaces  were  always  going  and 
the  fires  could  not  be  put  out  without  too  much  expense 
and  inconvenience. 

Twenty-two  different  kinds  of  paints  were  tested  in 
this  manner,  no  two  showing  similar  results.  The  author 
rather  than  allow  anyone  else  to  prepare  the  surface 
for  the  test  and  not  do  it  thoroughly,  did  so  himself,  so 
that  the  experience  thus  gained  would  be  of  subsequent 
value.  Plate  III  shows  the  author  scraping  the  hottest 
portion  of  the  stack  which  was  to  be  tested.  This  opera- 
tion was  followed  by  the  painter. 

Flames  were  bursting  forth  from  the  tops  of  the 
first,  second,  third  and  fifth  stacks,  and  the  roofs  were 
so  hot  that  the  soles  of  the  shoes  were  scorched,  and 
those  making  the  test  were  compelled  to  keep  moving. 
Vapor  can  be  seen  coming  from  the  wet  paint  on  the 
second  stack,  and  the  paint  brush  had  to  be  moved  fast 
in  order  to  keep  the  bristles  from  burning.  The  scraping 
tools  became  so  hot  from  induction  that  they  were 
handled  with  difficulty. 

Plate  IV  shows  the  tools  that  were  available  for 
cleaning  at  the  time,  and  Plate  V  shows  rust  scales  and 
old  paint  scales  (one-quarter  the  diameter)  removed. 

Red  heat  of  steel  or  iron  is  over  900  degrees  F.  and  the 
author  knows  of  no  vehicle  that  wrill  stand  this  heat  and 
be  water  proof  and  rust  preventing  at  the  same  time. 

Whitewash  or  calcimine,  sometimes  called  water 
paints,  and  sodium  silicate  used  as  a  vehicle,  will  stand 
much  more  than  900  degrees  F.,  but  paints  made  of  these 
will  not  stand  water  or  moisture,  nor  will  they  stick  to 
the  surface  long  after  being  thoroughly  hardened.  Only 
one  coat  of  paint  is  recommended  by  the  author  for  this 
class  of  work,  for  the  reason  that  extremely  hot  sur- 
faces usually  burn  off  the  paint  prematurely,  in  which 
case  frequent  applications  are  necessary,  and  two  coats 
would  be  a  considerable  expense  in  so  doing.  It  would 

40 


be  folly,  however,  to  expect  to  keep  paint  in  a  good  con- 
dition for  more  than  a  few  months  on  a  surface  as  hot 
as  900  degrees  F.  The  nearest  material  approaching  a 
protective  coating  to  stand. over  900  degrees  F.  would  be 
a  coating  of  porcelain  enamel.  This  would  take  more  heat 
than  2000  degrees  F.  to  melt  it  on  the  surface,  and  for 


Plate  IV. 


this  reason  it  would  be  an  expensive  and  impractical 
operation,  possible  only  on  new  work  while  in  the  factory 
preparatory  to  erection.  f 

An  approximate  estimate  of  temperatures  on  a  metal 
surface  may  'be  had  toy  applying  liquids  of  known  boiling 
points  on  the  surface  and  noting  if  they  'boil. 

No.  6.  Extraordinary  exposure  to  cold  generally  takes 


iii  conditions  such  as  cold  storage  plants  having  steel  con- 
struction within,  the  inside  surface  of  steel  plates  com- 
posing ships  bottoms,  the  outside  surface  of  standpipes 
or  water  cylinders  of  hydraulic  pumps,  &c.  The  varia- 
tions of  temperature  on  these  surfaces  are  slight  or  are 
below  the  amount  necessary  to  injure  a  paint  for  the  rea- 


Plate  V. 

son  that  they  rarely  if  ever  reach  higher  than  TO  degrees 
F.  The  greatest  amount  of  injury  which  these  conditions 
inflict  to  a  paint  is  due  to  chilled  vapor  resulting  from 
a  damp  atmosphere  condensing  on  the  surface  resembling 
sweat.  Should  the  conditions  be  such  that  this  sweat 
reappears  soon  after  it  has  been  removed,  preventing  the 
maintenance  of  a  dry  surface  long  enough  to  apply  the 

42 


paint  and  enable  it  to  become  dry,  the  painting  should  'be 
deferred  until  the  proper  condition  can  be  met  with  and 
then  paint  that  will  dry  and  harden  quickly  should  be 
used.  This  will  necessitate  the  use  of  a  paint  which  has 
very  little  or  no  oxidizing  oil. 

A  volatile  solvent  varnish  vehicle  paint  containing 
graphite  for  a  pigment  and  a  soluble  solid  known  to  the 
author  as  Nicaragua  gum.  has  been  found  to  foe  the  'best 
for  this  class  of  work.  This  kind  of  paint  hardens  so 
thoroughly  and  so  quickly  that  it  would  not  stand  such 
exposures  as  class  No.  2  with  any  degree  of  certainty 
or  satisfaction,  and  therefore  should  only  'be  used  for  ex- 
posures of  this  class. 

No.  7.  Extraordinary  exposures  to  liquids  takes  in  a 
class  where  water  is  maintained  in  direct  contact  with  the 
paint,  such  as  ships  'bottoms,  steel  intake  cribs,  tanks, 
standpipes  and  portions  of  gas  storage  tanks  commonly 
called  gas  holders.  These  require  a  compound  vehicle 
paint  with  very  little  oil,  or  a  varnish  paint  similar  to 
that  used  for  class  No.  6,  but  should  be  heavier  bodied 
and  contain  less  volatile  solvent,  so  that  a  heavy  coat- 
ing of  the  basic  material  will  remain  on  the  surface. 
This  is  necessary  to  withstand  the  extreme  aqueous  pres- 
sure against  the  paint  film. 

No.  8.  Extraordinary  exposure  to  abrasion  takes  in  a 
class  where  friction  eliminates  a  paint  from  a  surface  be- 
fore it  gets  a  chance  to  demonstrate  its  preserving  proper- 
ties by  virtue  of  exposure  to  atmosphere,  heat,  gases  or 
water,  such  as  coal  bunkers,  ships'  holds,  freight  cars  and 
metallic  shields  underneath  the  flooring  of  bridges  under 
which  locomotives  pass  emitting  carbonaceous  grit  from 
the  smokestacks. 

This  class  of  paint  should  be  slightly  harder  than  that 
used  for  exposure  No.  2,  but  not  hard  enough  to  become 
cracked  or  broken  by  violent  blows,  such  as  that  of  coal 
being  loaded  into  cars  and  striking  the  surface  of  the 
car.  It  should  have  graphite  exclusively  for  a  pigment. 
This  paint  when  almost  dry  should  be  dusted  with  the 
best  quality  of  slippery  dry  graphite,  then  allowed  to 
dry  and  then  polished  with  a  woolen  swab  or  sheep  skins 
with  the  wool  on  (using  the  wooly  side).  The  finished 
surface  will  then  have  a  highly  glazed  surface  that  will 
withstand  more  mechanical  abrasion  than  any  othei-  form 
of  paint  coating  which  the  author  knows  of. 


43 


Chapter  VII. 

The  Selection  of  the  Most  Suitable  Preservative. 

The  selection  of  the  most  suitable  material  should  be 
governed  not  only  by  the  class  of  exposure  to  be  met 


Plate  VI. 

with,  but  also  the  number  of  coats  of  paint  to  be  used 
and  the  time  allowed  for  it  to  dry  properly. 

Plate  VI   shows  two  samples  selected  from   several 

44 


hundred  of  which  the  author  has  been  giving:  thorough 
time  tests.  These  samples  were  exposed  in  the  Pitts- 
burgh District,  where  the  atmosphere  is  surcharged  with 
sulphuretted  hydrogen,  carbon  dioxide  and  sulphur  fumes, 
&e.  The  paint  was  applied  on  bright,  smooth  sheets  of 


Plate  VII. 

steel.  No.  IV  shows  an  improperly  prepared  graphite 
paint  and  No.  VII  shows  a  properly  prepared  graphite 
paint. 

One  shows  that  before  the  end  of  four  years  the 
protective  qualities  of  the  paint  were  exhausted  and  the 
steel  to  be  badly  eaten  with  rust.  The  other  shows  that 

45 


the  protective  qualities  of  the  paint  were  not  impaired 
during  the  same  length  of  time,  the  metal  remaining  as 
bright  underneath  the  coating  of  paint  as  the  day  it  was 
applied. 

No.  IV  was  taken  from  the  regular  stock  paint  of  "  a 
get  rich  quick "  paint  concern  and  was  advertised  as 
"  their  best  grade  "  and  the  "  best  paint  in  the  world." 

No.  VII  was  manufactured  by  a  concern  who  does  not 
make  bombastic  claims  for  their  products,  but  depend 
upon  their  reputation  for  their  continuance  in  business. 

An  enormous  spreading  capacity  of  a  paint  is  often  a 
misleading,  fradulent  or  deceptive  proposition  offered  to 
purchasers  of  paint  in  order  to  secure  their  patronage. 
The  spreading  capacity  of  almost  any  paint  of  good  body 
may  be  increased  by  thinning  it  considerably  with  a 
volatile  or  a  drying  oil,  and  this  decreases  the  cost  per 
gallon  by  reason  of  the  increased  bulk  resulting  from 
its  extension  by  the  use  of  a  cheaper  thinning  material 
than  the  cost  of  the  paint.  Therefore  claims  for  supe- 
riority of  a  paint  due  to  its  superior  spreading  capacity 
should  not  necessarily  add  anything  to  the  value  to  a 
statement  of  this  sort.  Furthermore,  the  less  spreading 
capacity  a  paint  has  the  more  body  it  possesses.  This 
body  is  generally  the  most  costly  part  of  a  paint,  and 
the  fact  that  it  is  too  heavy  or  thick  to  possess  spreading 
qualities  equal  to  a  thinner  paint  should  not  detract  from 
its  value  after  taking  into  consideration  the  cost  of  the 
thinners  necessary  to  reduce  the  body  and  increase  the 
quantity  and  spreading  capacity  to  the  extent  most  de- 
sired. 

A  basis  whereby  deductions  may  be  made  to  approxi- 
mate the  average  thickness  of  a  coat  of  paint  on  a  smooth 
flat  surface,  which  does  not  absorb  any  of  the  paint,  may 
be  readily  calculated  in  the  following  manner : 

A  legal  standard  United  States  gallon  we  know  must 
contain  231  cu.  in.,  and  if  1  gal.  of  paint  is  spread  over 
a  surface  containing  231  sq.  ft.,  the  wet  paint  will  average 
1-144  in.  thick. 

In  like  manner  should  the  paint  be  spread  twice  as 
far  and  cover  462  square  feet  to  the  gallon  it  would  be 
1-288  in.  which  thickness  can  be  compared  to  the  thick- 
ness of  the  leaves  of  a  book  having  288  pages  to  the  inch. 
Now  when  the  paint  is  dry  it  will  either  thicken  or  be- 
come thinner — the  former  if  a  linseed  oil  paint  and  the 

46 


latter  if  a  volatile  oil  varnish  paint — therefore  allow- 
ances should  be  made  accordingly. 

The  writer  believes  that  a  protective  coating  averag- 
ing less  than  1-144  in.  thick  is  not  sufficient  protection 
to  a  metal  surface  exposed  to  any  class  of  exposure  in- 
tended for  long  service  and  that  1-72  in.  is  not  necessary 
in  any  case  where  high  grade  material  is  used. 

The  spreading  capacity  of  a  paint  should  be  averaged 
when  based  upon  a  standard  condition  of  surface  the 


1  GALLON 
OF  PAINT 


1  SQUARE    FOOT 
144  SQUARE   INCHES 


most  suitable  for  the  purpose  being  bright  clean  tin 
sheets  or  glass  and  estimates  for  other  forms  of  surfaces 
based  upon  variations  from  the  standard.  The  spread- 
ing capacity  will  also  depend  upon  the  temperature  and 
for  convenience  70  degrees  F.  is  recommended. 

Careful  and  slovenly  spreading  of  paint  will  cause 
a  great  variation  and  lack  uniformity  of  thickness  of  a 
coating,  nevertheless  in  any  case  the  attainment  of  an 
average  estimate  of  thickness  can  not  be  depended  upon. 
When,  however,  a  paint  is  advertised  to  cover  1000  sq. 
ft.  to  the  gallon  it  means  necessarily  that  the  coating 
must  average  less  than  1-576  of  an  inch  thick  which  may 
be  compared  to  thin  tissue  paper. 


47 


Pigments  may  easily  be  tested  for  their  fineness  of 
texture  by  simply  rubbing  them  in  a  dry  state  between 
the  fingers  or  upon  the  palm  of  the  hand,  and  if  the 
pigment  is  mixed  in  a  drying  oil  it  can  be  separated  out 
and  dried  by  thinning  the  paint  with  gasoline,  vigorously 
shaking  together  the  mixture  allowing  the  pigment  to 
settle  to  the  bottom,  and  washing  out  the  heavy  oil,  then 
pouring  off  the  liquid,  repeating  the  operation  until  all 
of  the  drying  oils  have  been  extracted,  after  which  the 
pigment  may  be  dumped  out  upon  a  sheet  of  blotting 
paper  and  allowed  to  dry. 

It  will  be  noticed  that  the  best  grades  of  graphite 
"  rub  up  "  into  a  higher  gloss  between  the  fingers  than 
any  other  known  paint  pigment  and  that  when  this  pig- 
ment does  not  "  rub  up "  into  a  slippery  finish  it  is 
adulterated. 

Vehicles  may  be  tested  in  a  simple  way  for  com- 
mercial purposes  by  allowing  the  pigment  to  settle  to 
the  bottom,  pouring  the  vehicle  upon  a  piece  of  glass,  al- 
lowing it  to  dry  for  48  hours  and  then  subjecting  it  to  a 
temperature  of  say  200  degrees  F.  (up  near  a  hot  stove) 
for  several  hours,  after  which  cool  off  by  soaking  it  into 
cold  water  for  30  minutes,  wipe  dry  with  a  cloth  vigor- 
ously and  see  whether  any  of  it  will  rub  off,  after  which 
take  the  blade  of  a  pocket  knife  and  cut  into  it  with  a 
long  steady  cut  beneath  the  paint  and  along  the  surface 
of  the  glass.  If  the  vehicle  can  be  then  cut  leaving  long 
tough  and  elastic  strips  it  can  reasonably  be  expected 
to  possess  good  qualifications  for  ordinary  exposures  met 
with.  However  for  exposures  such  as  3,  4,  5,  0,  7  and  S 
they  should  in  addition  be  given  actual  time  tests  to 
the  exact  exposures  to  be  met  with,  keeping  detailed  ac- 
counts of  the  conditions  and  the  kind,  quality  and 
amount  of  raw  materials  used,  so  that  the  paints  thus 
prepared  for  use  may  be  intelligently  compared  for  future 
selection. 

Driers  should  be  given  the  same  test  as  the  vehicle, 
noting,  however,  the  strength  of  the  drying  properties,  by 
the  amount  necessary  for  use  with  the  vehicle  and  the 
time  consumed  in  the  drying  of  the  oils  thus  tested. 

A  paint  oil  or  varnish  is  considered  by  the  author 
to  be  perfectly  dry  at  such  time  when  at  a  temperature 
of  70  degrees  F.  it  refuses  to  adhere  to  a  sheet  of  writ- 
ing paper  smoothed  over  it  and  pressed  down  hard  by 
the  palm  of  the  hand.  This  condition  at  the  very  least 


should  prevail  before  additional  coats  of  paint  are  ap- 
plied. 

However  as  much  additional  time  as  this  condition 
requires  to  consume  should  be  given  before  the  same  is 
attempted. 

Volatile  oils  may  be  tested  by  allowing  them  to 
evaporate  from  a  sheet  of  glass  and  noting  whether 
there  is  a  greasy  deposit  left  on  the  surface,  which  if  so, 
shows  a  substance  which  when  entering  into  the  liquid 
portion  of  a  paint  will  seriously  prevent  the  drying  of 
it  and  cause  an  endless  amount  of  annoyance,  sometimes 
necessitating  the  removal  of  the  paint  entirely,  which  if 
not  done  would  prevent  the  proper  adhesion  of  more 
coats  of  paint. 

A  great  deal  more  might  be  stated  relative  to  the 
testing  of  materials. 

The  writer  has  noticed  that  the  signs  of  the  times 
show  an  increasing  tendency  unfortunately  on  the  part 
of  the  general  property  owner  to  leave  the  question  of 
maintenance  and  selection  of  materials  to  others.  The 
luxurious  modes  of  entertainment  now  prevalent  entice 
the  property-owner  to  more  pleasant  occupations  during 
the  intervals  of  the  rush  of  business  than  formerly,  when 
each  property  owner  not  only  painted  his  own  house 
but  made  his  own  paint  and  made  it  to  last. 


49 


Chapter  VIII. 

Deductions  and  Conclusions. 

After  pursuing  the  subject  of  rust  prevention  it  be- 
comes very  apparent  that  many  questions  are  involved 
that  do  not  clear  the  way,  for  those  who  cannot  give  it 
much  thought  or  attention. 

It  does  not  take  much  of  either,  however,  to  deduce 
the  following  facts: 

1.  The  property  owner   should   be    satisfied  that  the 
surface  to  be  protected  is  as  clean,  dry,  smooth  and  firm 
as  it  is  possible  to  get  it  before  his  time,  money  or  pa- 
tience is  expended  thereon.    Without  this  important  con- 
dition any  means  to  be  employed  would  only  be  wasted. 
Inasmuch  as  the  preparation  of  the  surface,  the  employ- 
ment of  the  proper  kind  of  material  and  the  quality  of 
work  done,  when  undertaken  by  a  contractor  may  easily 
be  manipulated  by  him  in  such  a  way  that  he  may  greatly 
profit  financially  to  the  detriment  of  the  owner,   it  is 
recommended  that  the  owner  purchase  his  own  material 
direct  and  hire  his  men  by  the  day  to  do  the  work.    Even 
should  the  men  put  in  more  time  than  necessary,   the 
chances  are  that  the  work  will  not  have  been  slighted,  and 
that  the  total  cost  of  the  job  would  be  much  less  than  the 
same  quality  of  work  and  materials  would  be  supplied  by 
the  contractor. 

2.  The  owner  should  purchase  his  paint  in  different 
shades,  using  a  different  shade  for  each  coat,  so  that  the 
detection  of  omissions  in  thoroughly  covering  the  surface 
may  be  readily  accomplished.    The  paint  should  be  deliv- 
ered on  the  ground  in  sealed  packages  guaranteed  by  the 
most  responsible  maker  in  whom  the  purchaser  may  have 
confidence. 

3.  It  should  be  contained  in  receptacles  that  will  main- 
tain it  in  a  good  condition,   and  enable  it  to  be  thor- 
oughly mixed  or  agitated  during  the  progress  of  the  work, 
so  that  the  paint  thus  used  is  of  a  uniform  consistency 
until  the  work  in  hand  is  fully  completed. 

Rain,  dust,  sand,  mortar,  plaster  or  refuse  from  build- 
ings close  by  have  often  found  its  way  into  the  paint 
barrel,  rendering  the  contents  unfit  for  use. 

The  great  difference  in  the  specific  gravity  between 

50 


pigment  and  vehicle  causes  the  former  to  readily  precipi- 
tate to  the  bottom  in  a  very  short  time,  even  in  the  very 
best  paints,  and  the  best  results  can  only  be  obtained  by 
energetically  keeping  the  paint  stirred  up. 

The  great  drawback  to  the  ordinary  paint  barrel  is 
due  to  the  fact  that  the  head  must  be  removed  in  order 
to  thoroughly  agitate  the  contents  by  means  of  a  board 
or  paddle. 

To   remove  the  head   without  destroying  the  barrel 


(which  cost  generally  over  $1.50  each)  two  or  three  hoops 
must  be  driven  up  to  allow  the  staves  to  spread  at  the 
top,  so  that  the  head  can  be  disengaged  from  the  chime. 
When  the  staves  spread  in  this  manner  openings  are  left 
between  them,  allowing  the  paint  to  run  out,  entailing 
waste  and  loss  of  time  tightening  up  the  barrel  again. 

Barrels    containing    various    kinds    of    paint   mixers 
have    frequently    been    tried,    but    almost    always    have 


proven  either  complete  failures,  or  so  unreliable  that  de 
pendence  upon  them  results  invariable  in  the  abandon 
ment  of  their  use. 

An  ordinary  barrel  filled  with  good  paint  contains  sev- 
eral hundred  pounds  of  pigment,  which  when  settled  to 
the  bottom  becomes  tough  like  putty. 

The  barrel  paint  mixers  that  have  been  tried  becomes 
imbedded  in  the  pigment  and  stuck  fast  with  as  much 
resistance  apparently  as  would  be  experienced  trying  to- 
turn  a  spade  around  when  it  is  shoved  down  deeply  in 
firm  soil. 

•  These  drawbacks  have  led  the  writer  into  experiments 
resulting  in  the  construction  of  a  barrel  paint  mixer 
which  is  recommended  to  do  the  work. 

The  stem  and  crank  as  seen  in  the  above  illustration 
(1A,  2A,  3A)  is  made  of  a  one-piece  malleable  casting, 
and  the  side  arms  or  paddles  are  made  of  stiff  spring 
steel  y8  in.  thick.  These  side  arms  are  connected  by 
means  of  loosely  fitting  rivets,  and  may  be  drawn  up 
edgewise  through  the  pigment  so  as  to  fold  up,  thereby 
reducing  the  diameter  of  the  agitating  surface,  so  that  a 
portion  of  the  pigment  may  be  moved  and  mixed  with  the 
vehicle;  after  this  is  done  the  agitator  paddles  may  be 
spread  out  as  required  until  the  whole  width  may  be  used 
for  all  of  the  pigment  at  one  operation. 

The  mixer  should  be  turned  rapidly  to  the  right  for 
8  or  10  revolutions,  and  then  reversed  quickly,  this  gen- 
erates an  undercurrent  coming  from  the  top  in  the  form 
of  a  whirlpool,  and  leaves  nothing  to  be  desired  in  the 
matter  of  thorough  agitation. 

It  is  an  important  fact  that  the  first  coat  of  paint 
usually  applied  by  the  manufacturers  on  newly  made 
metal  work  is  of  the  cheapest  variety,  unless  specifica- 
tions and  contracts  to  the  contrary  offset  this  result. 

Every  owner  of.  property  containing  metal  work  that 
needs  protection  should  thoroughly  understand  "  what  he 
needs  as  a  preservative,  and  demand  that  it  be  properly 
applied  by  the  painter." 

Paint  should  be  spread  on  a  surface  in  temperatures 
between  50  and  90  degrees  F.,  and  should  be  spread  on 
carefully  that  all  air  bubbles  under  the  paint  should  be 
eliminated. 

The  application  of  paint  with  a  machine  or  spray 
should  not  be  encouraged,  for  the  reason  that  air  bub- 
bles get  under  the  fine  spray  and  prevent  the  close  ad- 

52 


herence  of  the  paint  to  the  surface,  and  also  has  a  tend- 
ency to  aerate  the  paint.  The  first  coat  on  metal  should 
not  be  quite  as  elastic  as  the  succeeding  coats.  It  should 
dry  hard,  tough  and  slightly  yielding.  Its  subsequent 
hardening  is  somewhat  prevented  by  the  coat  on  top  of  it. 

The  last  coat,  or  top  coat,  should  dry  slower  than  the 
one  underneath,  so  as  to  withstand  the  drying  tendency 
of  the  weather  and  meet  expansion  and  contraction  where 
•  it  is  mostly  needed. 

Black  paints  are  the  most  opaque  and  should  be  used, 
not  only  because  the  material  out  of  which  they  can  be 
made  affords  the  production  of  the  best  protective  coat- 
ing, but  also  for  the  reason  that  it  presents  a  striking  con- 
trast to  the  color  of  rust  or  corrosion. 

When  red  or  brown  paints  are  used  the  appearance 
of  rust  can  only  be  detected  at  times  when  close  inspec- 
tion is  promoted,  and  this  is  very  often  deferred  by  over- 
sight or  neglect. 

Too  much  importance  cannot  be  attached  to  the  neces- 
sity of  preserving  metal  before  corrosion  or  oxidation 
has  taken  place. 

The  loss  that  generally  ensues  when  metal  surfaces 
are  not  continually  protected  in  every  corner  and  crevice 
is  rarely  appreciated.  The  wasted  metal  resulting  from 
one  moment's  chemical  action  can  never  be  replaced  to 
its  former  condition  (commercially  speaking),  and  the 
section  so  effected  is  ofttimes  so  very  difficult  and  costly 
to  replace,  especially  -in  hidden  structural  work  and 
bridges,  that  these  matters  are  in  many  cases  postponed 
until  the  whole  structure  becomes  condemned  as  dan- 
gerous and  a  new  one  needs  to  be  built. 

Care  should  be  employed  by  the  purchaser  of  new 
structural  work,  bridges  or  sheet  metal  work,  where  the 
protective  coating  is  furnished  by  the  contractor ;  in  see- 
ing to  the  explicit  and  proper  wording  of  the  specifica- 
tions so  that  the  right  brand,  make  and  best  paint  ma- 
terials are  clearly  defined  so  as  to  leave  no  valid  chance 
for  substitution.  This  rule  should  always  govern  wher- 
ever and  whenever  good  paint  is  wanted.  Specifications 
for  applying  the  paint  should  always  state  "  the  number 
of  coats  wanted  and  that  there  should  be  no  air  holes, 
moisture,  oil,  grease  or  dirt  under  the  paint ;  that  it 
should  be  well  brushed  on  by  hand  to  a  thoroughly 
cleaned  and  dry  surface,  thoroughly  cover  the  said  sur- 
face and  be  applied  in  dry  weather  between  temperatures 

53 


of  50  to  90  degrees  F.  (unless  the  paint  is  a  special  kind 
and  is  shown  by  the  purchaser  to  especially  require  dif- 
ferent temperature  for  application"). 

This  should  never  be  left  for  engineers  to  do,  for  a 
wide  diversity  of  opinion  exists  as  to  what  make  or 
brand  should  be  used,  even  among  those  of  many  years' 
experience. 

Furthermore,  engineers  or  architects  very  often  re- 
fuse to  specify  any  particular  make  of  paint,  for  obvious 
reasons.  It  savors  of  partiality  and  leaves  room  for  se- 
vere criticism.  On  the  other  hand,  if  the  contractor  can 
evade  supplying  an  established  brand  of  high  grade  ma- 
terial and  suit  himself  in  the  furnishing  of  paint  made 
of  raw  materials  selected  by  himself,  rendering  it  im- 
possible for  the  engineer  (without  giving  the  material  a 
daily  chemical  analysis),  to  ascertain  its  true  value  he 
has  the  chance  to  utilize  the  greater  of  the  two  evils  to 
his  own  profit. 

In  cases  where  the  engineer  will  not  consult  with  the 
owner  on  the  brand  or  make  of  paint  to  be  used  and  spec- 
ify the  same  in  the  contracts,  the  author  suggests  that 
the  specifications  read  as  follows :  "  All  paint  and  paint 
materials  used  must  be  selected  or  approved  by  the 
owners  before  the  same  is  permitted  to  be  used.  It  shall 
be  subject  to  the  inspection  and  refusal  of  the  engineer 
when  the  same  is  not  branded  or  recognized  as  such." 
This  would  relieve  the  engineer  of  a  responsibility  which 
is  not  necessary  for  him  to  be  expected  to  shoulder. 

No  engineer,  in  designing  a  structure,  can  make  effi- 
cient allowance  for  decay,  for  the  reason  that  the  time, 
place  and  extent  of  such  action  is  an  unknown  quantity 
and  always  will  be. 

Loss  of  life  and  property  due  to  collapse  resulting 
from  decay  is  a  serious  theme  to  reflect  upon.  Any  ex- 
isting doubt  as  to  the  necessity  of  giving  the  work  a  good 
coat  of  good  paint  should  be  decided  upon  before  it  is 
too  late. 


54 


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